Merging upstream version 0.18.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 937 insertions, 297 deletions

diff --git a/docs/configuration.md b/docs/configuration.md
index addf0c0..af49d7c 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -11,7 +11,7 @@ gitlint generate-config
 You can also use a different config file like so:
 
 ```sh
-gitlint --config myconfigfile.ini 
+gitlint --config myconfigfile.ini
 ```
 
 The block below shows a sample `.gitlint` file. Details about rule config options can be found on the
@@ -39,16 +39,17 @@ ignore=title-trailing-punctuation, T3
 # precedence over this
 verbosity = 2
 
-# By default gitlint will ignore merge, revert, fixup and squash commits.
+# By default gitlint will ignore merge, revert, fixup, fixup=amend, and squash commits.
 ignore-merge-commits=true
 ignore-revert-commits=true
 ignore-fixup-commits=true
+ignore-fixup-amend-commits=true
 ignore-squash-commits=true
 
-# Ignore any data send to gitlint via stdin
+# Ignore any data sent to gitlint via stdin
 ignore-stdin=true
 
-# Fetch additional meta-data from the local repository when manually passing a 
+# Fetch additional meta-data from the local repository when manually passing a
 # commit message to gitlint via stdin or --commit-msg. Disabled by default.
 staged=true
 
@@ -58,6 +59,11 @@ staged=true
 # Disabled by default.
 fail-without-commits=true
 
+# Whether to use Python `search` instead of `match` semantics in rules that use
+# regexes. Context: https://github.com/jorisroovers/gitlint/issues/254
+# Disabled by default, but will be enabled by default in the future.
+regex-style-search=true
+
 # Enable debug mode (prints more output). Disabled by default.
 debug=true
 
@@ -187,7 +193,7 @@ gitlint-ignore: all
 
 `gitlint-ignore: all` can occur on any line, as long as it is at the start of the line.
 
-You can also specify specific rules to be ignored as follows: 
+You can also specify specific rules to be ignored as follows:
 ```
 WIP: This is my commit message
 
@@ -201,7 +207,7 @@ gitlint-ignore: T1, body-hard-tab
 gitlint configuration is applied in the following order of precedence:
 
 1. Commit specific config (e.g.: `gitlint-ignore: all` in the commit message)
-2. Configuration Rules (e.g.: [ignore-by-title](/rules/#i1-ignore-by-title))
+2. Configuration Rules (e.g.: [ignore-by-title](rules.md#i1-ignore-by-title))
 3. Commandline convenience flags (e.g.:  `-vv`, `--silent`, `--ignore`)
 4. Environment variables (e.g.: `GITLINT_VERBOSITY=3`)
 5. Commandline configuration flags (e.g.: `-c title-max-length=123`)
@@ -216,9 +222,9 @@ using commandline flags or in `[general]` section in a `.gitlint` configuration
 
 Enable silent mode (no output). Use [exit](index.md#exit-codes) code to determine result.
 
-Default value  |  gitlint version | commandline flag  | environment variable
----------------|------------------|-------------------|-----------------------
-`False`        | >= 0.1.0         | `--silent`        | `GITLINT_SILENT`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| `False`       | >= 0.1.0        | `--silent`       | `GITLINT_SILENT`     |
 
 #### Examples
 ```sh
@@ -226,14 +232,15 @@ Default value  |  gitlint version | commandline flag  | environment variable
 gitlint --silent
 GITLINT_SILENT=1 gitlint  # using env variable
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### verbosity
 
 Amount of output gitlint will show when printing errors.
 
-Default value  |  gitlint version | commandline flag  | environment variable 
----------------|------------------|-------------------|-----------------------
-3              | >= 0.1.0         | `-v`              | `GITLINT_VERBOSITY`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| 3             | >= 0.1.0        | `-v`             | `GITLINT_VERBOSITY`  |
 
 
 #### Examples
@@ -252,14 +259,15 @@ GITLINT_VERBOSITY=2 gitlint    # using env variable
 [general]
 verbosity=2
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### ignore
 
 Comma separated list of rules to ignore (by name or id).
 
-Default value              |  gitlint version | commandline flag  | environment variable   
----------------------------|------------------|-------------------|-----------------------
- [] (=empty list)          | >= 0.1.0         | `--ignore`        | `GITLINT_IGNORE`
+| Default value    | gitlint version | commandline flag | environment variable |
+| ---------------- | --------------- | ---------------- | -------------------- |
+| [] (=empty list) | >= 0.1.0        | `--ignore`       | `GITLINT_IGNORE`     |
 
 #### Examples
 ```sh
@@ -274,14 +282,15 @@ GITLINT_IGNORE=T1,body-min-length gitlint     # using env variable
 [general]
 ignore=T1,body-min-length
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### debug
 
 Enable debugging output.
 
-Default value  |  gitlint version | commandline flag  | environment variable   
----------------|------------------|-------------------|-----------------------
- false         | >= 0.7.1         | `--debug`         | `GITLINT_DEBUG`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| false         | >= 0.7.1        | `--debug`        | `GITLINT_DEBUG`      |
 
 #### Examples
 ```sh
@@ -291,14 +300,15 @@ GITLINT_DEBUG=1 gitlint # using env variable
 # --debug is special, the following does NOT work
 # gitlint -c general.debug=true
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### target
 
 Target git repository gitlint should be linting against.
 
-Default value              |  gitlint version | commandline flag  | environment variable   
----------------------------|------------------|-------------------|-----------------------
-(empty)                    | >= 0.8.0         | `--target`        | `GITLINT_TARGET`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| (empty)       | >= 0.8.0        | `--target`       | `GITLINT_TARGET`     |
 
 #### Examples
 ```sh
@@ -312,14 +322,31 @@ GITLINT_TARGET=/home/joe/myrepo/ gitlint     # using env variable
 [general]
 target=/home/joe/myrepo/
 ```
+------------------------------------------------------------------------------------------------------------------------
+
+### config
+
+Path where gitlint looks for a config file.
+
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| `.gitlint`    | >= 0.1.0        | `--config`       | `GITLINT_CONFIG`     |
+
+#### Examples
+```sh
+gitlint --config=/home/joe/gitlint.ini
+gitlint -C /home/joe/gitlint.ini      # different way of doing the same
+GITLINT_CONFIG=/home/joe/gitlint.ini  # using env variable
+```
+------------------------------------------------------------------------------------------------------------------------
 
 ### extra-path
 
 Path where gitlint looks for [user-defined rules](user_defined_rules.md).
 
-Default value              |  gitlint version | commandline flag  | environment variable   
----------------------------|------------------|-------------------|-----------------------
- (empty)                   | >= 0.8.0         | `--extra-path`    | `GITLINT_EXTRA_PATH`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| (empty)       | >= 0.8.0        | `--extra-path`   | `GITLINT_EXTRA_PATH` |
 
 #### Examples
 ```sh
@@ -333,14 +360,14 @@ GITLINT_EXTRA_PATH=/home/joe/rules/ gitlint     # using env variable
 [general]
 extra-path=/home/joe/rules/
 ```
-
+------------------------------------------------------------------------------------------------------------------------
 ### contrib
 
-Comma-separated list of [Contrib rules](contrib_rules) to enable (by name or id).
+Comma-separated list of [Contrib rules](contrib_rules.md) to enable (by name or id).
 
-Default value              |  gitlint version | commandline flag  | environment variable   
----------------------------|------------------|-------------------|-----------------------
- (empty)                   | >= 0.12.0        | `--contrib`       | `GITLINT_CONTRIB`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| (empty)       | >= 0.12.0       | `--contrib`      | `GITLINT_CONTRIB`    |
 
 #### Examples
 ```sh
@@ -349,21 +376,31 @@ gitlint --contrib=contrib-title-conventional-commits,CC1
 # different way of doing the same
 gitlint -c general.contrib=contrib-title-conventional-commits,CC1
 # using env variable
-GITLINT_CONTRIB=contrib-title-conventional-commits,CC1 gitlint   
+GITLINT_CONTRIB=contrib-title-conventional-commits,CC1 gitlint
 ```
 ```ini
 #.gitlint
 [general]
 contrib=contrib-title-conventional-commits,CC1
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### staged
 
-Fetch additional meta-data from the local repository when manually passing a commit message to gitlint via stdin or `--commit-msg`.
+Attempt smart guesses about meta info (like author name, email, branch, changed files, etc) when manually passing a
+commit message to gitlint via stdin or `--commit-msg`.
+
+Since in such cases no actual git commit exists (yet) for the message being linted, gitlint
+needs to apply some heuristics (like checking `git config` and any staged changes) to make a smart guess about what the
+likely author name, email, commit date, changed files and branch of the ensuing commit would be.
+
+When not using the `--staged` flag while linting a commit message via stdin or `--commit-msg`, gitlint will only have
+access to the commit message itself for linting and won't be able to enforce rules like
+[M1:author-valid-email](rules.md#m1-author-valid-email).
 
-Default value  |  gitlint version | commandline flag  | environment variable   
----------------|------------------|-------------------|-----------------------
- false         | >= 0.13.0        | `--staged`        | `GITLINT_STAGED`
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| false         | >= 0.13.0       | `--staged`       | `GITLINT_STAGED`     |
 
 #### Examples
 ```sh
@@ -377,6 +414,7 @@ GITLINT_STAGED=1 gitlint       # using env variable
 [general]
 staged=true
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### fail-without-commits
 
@@ -384,15 +422,15 @@ Hard fail when the target commit range is empty. Note that gitlint will
 already fail by default on invalid commit ranges. This option is specifically
 to tell gitlint to fail on **valid but empty** commit ranges.
 
-Default value  |  gitlint version | commandline flag  | environment variable   
----------------|------------------|---------------------------|-----------------------
- false         | >= 0.15.2        | `--fail-without-commits`  | `GITLINT_FAIL_WITHOUT_COMMITS`
+| Default value | gitlint version | commandline flag         | environment variable           |
+| ------------- | --------------- | ------------------------ | ------------------------------ |
+| false         | >= 0.15.2       | `--fail-without-commits` | `GITLINT_FAIL_WITHOUT_COMMITS` |
 
 #### Examples
 ```sh
 # CLI
 # The following will cause gitlint to hard fail (i.e. exit code > 0)
-# since HEAD..HEAD is a valid but empty commit range. 
+# since HEAD..HEAD is a valid but empty commit range.
 gitlint --fail-without-commits --commits HEAD..HEAD
 GITLINT_FAIL_WITHOUT_COMMITS=1 gitlint       # using env variable
 ```
@@ -402,13 +440,79 @@ GITLINT_FAIL_WITHOUT_COMMITS=1 gitlint       # using env variable
 fail-without-commits=true
 ```
 
+---
+### regex-style-search
+
+Whether to use Python `re.search()` instead of `re.match()` semantics in all built-in rules that use regular expressions. 
+
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| false         | >= 0.18.0       | Not Available    | Not Available        |
+
+!!! important
+    At this time, `regex-style-search` is **disabled** by default, but it will be **enabled** by default in the future.
+    
+
+
+Gitlint will log a warning when you're using a rule that uses a custom regex and this option is not enabled:
+
+```plain
+WARNING: I1 - ignore-by-title: gitlint will be switching from using Python regex 'match' (match beginning) to
+'search' (match anywhere) semantics. Please review your ignore-by-title.regex option accordingly.
+To remove this warning, set general.regex-style-search=True. 
+More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
+```
+
+*If you don't have any custom regex specified, gitlint will not log a warning and no action is needed.*
+
+**To remove the warning:** 
+
+1. Review your regex in the rules gitlint warned for and ensure it's still accurate when using [`re.search()` semantics](https://docs.python.org/3/library/re.html#search-vs-match).
+2. Enable `regex-style-search` in your `.gitlint` file (or using [any other way to configure gitlint](http://127.0.0.1:8000/gitlint/configuration/)):
+
+```ini
+[general]
+regex-style-search=true
+```
+
+#### More context
+Python offers [two different primitive operations based on regular expressions](https://docs.python.org/3/library/re.html#search-vs-match): 
+`re.match()` checks for a match only at the beginning of the string, while `re.search()` checks for a match anywhere
+in the string.
+
+
+
+Most rules in gitlint already use `re.search()` instead of `re.match()`, but there's a few notable exceptions that
+use `re.match()`, which can lead to unexpected matching behavior.
+
+- M1 - author-valid-email
+- I1 - ignore-by-title
+- I2 - ignore-by-body
+- I3 - ignore-body-lines
+- I4 - ignore-by-author-name
+
+The `regex-style-search` option is meant to fix this inconsistency. Setting it to `true` will force the above rules to
+use `re.search()` instead of `re.match()`. For detailed context, see [issue #254](https://github.com/jorisroovers/gitlint/issues/254).
+
+
+#### Examples
+```sh
+# CLI
+gitlint -c general.regex-style-search=true
+```
+```ini
+#.gitlint
+[general]
+regex-style-search=true
+```
+------------------------------------------------------------------------------------------------------------------------
 ### ignore-stdin
 
 Ignore any stdin data. Sometimes useful when running gitlint in a CI server.
 
-Default value  |  gitlint version | commandline flag  | environment variable   
----------------|------------------|-------------------|-----------------------
- false         | >= 0.12.0        | `--ignore-stdin`  | `GITLINT_IGNORE_STDIN`
+| Default value | gitlint version | commandline flag | environment variable   |
+| ------------- | --------------- | ---------------- | ---------------------- |
+| false         | >= 0.12.0       | `--ignore-stdin` | `GITLINT_IGNORE_STDIN` |
 
 #### Examples
 ```sh
@@ -422,14 +526,15 @@ GITLINT_IGNORE_STDIN=1 gitlint       # using env variable
 [general]
 ignore-stdin=true
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### ignore-merge-commits
 
 Whether or not to ignore merge commits.
 
-Default value  |  gitlint version | commandline flag  | environment variable  
----------------|------------------|-------------------|-----------------------
- true          | >= 0.7.0         | Not Available     | Not Available  
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| true          | >= 0.7.0        | Not Available    | Not Available        |
 
 #### Examples
 ```sh
@@ -441,14 +546,15 @@ gitlint -c general.ignore-merge-commits=false
 [general]
 ignore-merge-commits=false
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### ignore-revert-commits
 
 Whether or not to ignore revert commits.
 
-Default value  |  gitlint version | commandline flag  | environment variable   
----------------|------------------|-------------------|-----------------------
- true          | >= 0.13.0        | Not Available     | Not Available  
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| true          | >= 0.13.0       | Not Available    | Not Available        |
 
 #### Examples
 ```sh
@@ -460,14 +566,15 @@ gitlint -c general.ignore-revert-commits=false
 [general]
 ignore-revert-commits=false
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ### ignore-fixup-commits
 
 Whether or not to ignore [fixup](https://git-scm.com/docs/git-commit#git-commit---fixupltcommitgt) commits.
 
-Default value  |  gitlint version | commandline flag  | environment variable  
----------------|------------------|-------------------|-----------------------
- true          | >= 0.9.0         | Not Available     | Not Available  
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| true          | >= 0.9.0        | Not Available    | Not Available        |
 
 #### Examples
 ```sh
@@ -479,14 +586,35 @@ gitlint -c general.ignore-fixup-commits=false
 [general]
 ignore-fixup-commits=false
 ```
+------------------------------------------------------------------------------------------------------------------------
+
+### ignore-fixup-amend-commits
+
+Whether or not to ignore [fixup=amend](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---fixupamendrewordltcommitgt) commits.
+
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| true          | >= 0.18.0       | Not Available    | Not Available        |
+
+#### Examples
+```sh
+# CLI
+gitlint -c general.ignore-fixup-amend-commits=false
+```
+```ini
+#.gitlint
+[general]
+ignore-fixup-amend-commits=false
+```
+------------------------------------------------------------------------------------------------------------------------
 
 ### ignore-squash-commits
 
 Whether or not to ignore [squash](https://git-scm.com/docs/git-commit#git-commit---squashltcommitgt) commits.
 
-Default value  |  gitlint version | commandline flag  | environment variable 
----------------|------------------|-------------------|-----------------------
- true          | >= 0.9.0         | Not Available     | Not Available  
+| Default value | gitlint version | commandline flag | environment variable |
+| ------------- | --------------- | ---------------- | -------------------- |
+| true          | >= 0.9.0        | Not Available    | Not Available        |
 
 #### Examples
 ```sh
diff --git a/docs/contrib_rules.md b/docs/contrib_rules.md
index 336e42a..e085f23 100644
--- a/docs/contrib_rules.md
+++ b/docs/contrib_rules.md
@@ -1,11 +1,12 @@
 # Using Contrib Rules
+
 _Introduced in gitlint v0.12.0_
 
 Contrib rules are community-**contrib**uted rules that are disabled by default, but can be enabled through configuration.
 
 Contrib rules are meant to augment default gitlint behavior by providing users with rules for common use-cases without
 forcing these rules on all gitlint users. This also means that users don't have to
-re-implement these commonly used rules themselves as [user-defined](user_defined_rules) rules.
+re-implement these commonly used rules themselves as [user-defined](user_defined_rules.md) rules.
 
 To enable certain contrib rules, you can use the `--contrib` flag.
 ```sh
@@ -42,6 +43,8 @@ ID    | Name                                | gitlint version   | Description
 ------|-------------------------------------|------------------ |-------------------------------------------
 CT1   | contrib-title-conventional-commits  | >= 0.12.0         | Enforces [Conventional Commits](https://www.conventionalcommits.org/) commit message style on the title.
 CC1   | contrib-body-requires-signed-off-by | >= 0.12.0         | Commit body must contain a `Signed-off-by` line.
+CC2   | contrib-disallow-cleanup-commits    | >= 0.18.0         | Commit title must not contain `fixup!`, `squash!`, `amend!`.
+CC3   | contrib-allowed-authors              | >= 0.18.0         | Enforce that only authors listed in the `AUTHORS` file are allowed to commit.
 
 ## CT1: contrib-title-conventional-commits ##
 
@@ -63,5 +66,18 @@ ID    | Name                                  | gitlint version    | Description
 CC1   | contrib-body-requires-signed-off-by   | >= 0.12.0          | Commit body must contain a `Signed-off-by` line. This means, a line that starts with the `Signed-off-by` keyword.
 
 
+## CC2: contrib-disallow-cleanup-commits ##
+
+ID    | Name                             | gitlint version    | Description
+------|----------------------------------|--------------------|-------------------------------------------
+CC2   | contrib-disallow-cleanup-commits | >= 0.18.0          | Commit title must not contain `fixup!`, `squash!` or `amend!`. This means `git commit --fixup` and `git commit --squash` commits are not allowed.
+
+## CC3: contrib-allowed-authors ##
+
+ID    | Name                             | gitlint version    | Description
+------|----------------------------------|--------------------|-------------------------------------------
+CC3   | contrib-allowed-authors           | >= 0.18.0          | The commit author must be listed in an `AUTHORS` file to be allowed to commit. Possible file names are also `AUTHORS.txt` and `AUTHORS.md`.
+
 ## Contributing Contrib rules
-We'd love for you to contribute new Contrib rules to gitlint or improve existing ones! Please visit the [Contributing](contributing) page on how to get started.
+
+We'd love for you to contribute new Contrib rules to gitlint or improve existing ones! Please visit the [Contributing](contributing.md) page on how to get started.
diff --git a/docs/contributing.md b/docs/contributing.md
index 1002676..254e856 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -6,7 +6,7 @@ The [source-code and issue tracker](https://github.com/jorisroovers/gitlint) are
 Often it takes a while for us (well, actually just [me](https://github.com/jorisroovers)) to get back to you
 (sometimes up to a few months, this is a hobby project), but rest assured that we read your message and appreciate
 your interest!
-We maintain a [loose roadmap on our wiki](https://github.com/jorisroovers/gitlint/wiki/Roadmap), but
+We maintain a [loose project plan on github projects](https://github.com/users/jorisroovers/projects/1/), but
 that's open to a lot of change and input.
 
 ## Guidelines
@@ -19,11 +19,15 @@ When contributing code, please consider all the parts that are typically require
 - [Integration tests](https://github.com/jorisroovers/gitlint/tree/main/qa) (also automatically
   [enforced by CI](https://github.com/jorisroovers/gitlint/actions)). Again, please consider writing new ones
   for your functionality, not only updating existing ones to make the build pass.
-- [Documentation](https://github.com/jorisroovers/gitlint/tree/main/docs)
+- [Documentation](https://github.com/jorisroovers/gitlint/tree/main/docs).
 
 Since we want to maintain a high standard of quality, all of these things will have to be done regardless before code
-can make it as part of a release. If you can already include them as part of your PR, it's a huge timesaver for us
-and it's likely that your PR will be merged and released a lot sooner. Thanks!
+can make it as part of a release. **Gitlint commits and pull requests are gated on all of our tests and checks as well as
+code-review**. If you can already include them as part of your PR, it's a huge timesaver for us
+and it's likely that your PR will be merged and released a lot sooner. 
+
+It's also a good idea to open an issue before submitting a PR for non-trivial changes, so we can discuss what you have
+in mind before you spend the effort. Thanks!
 
 !!! Important
     **On the topic of releases**: Gitlint releases typically go out when there's either enough new features and fixes
@@ -32,55 +36,105 @@ and it's likely that your PR will be merged and released a lot sooner. Thanks!
     or months before merged code actually gets released - we know that can be frustrating but please understand it's
     a well-considered trade-off based on available time.
 
-## Development
+## Local setup
 
-There is a Vagrantfile (Ubuntu) in this repository that can be used for development.
-It comes pre-installed with all Python versions that gitlint supports.
-```sh
-vagrant up
-vagrant ssh
-```
-
-Or you can choose to use your local environment:
+To install gitlint for local development:
 
 ```sh
 python -m venv .venv
 . .venv/bin/activate
-pip install --upgrade pip
 pip install -r requirements.txt -r test-requirements.txt -r doc-requirements.txt
 python setup.py develop
 ```
 
-To run tests:
+## Github Devcontainer
+
+We provide a devcontainer on github to make it easier to get started with gitlint development using VSCode.
+
+To start one, click the plus button under the *Code* dropdown on
+[the gitlint repo on github](https://github.com/jorisroovers/gitlint). 
+
+**It can take ~15min for all post installation steps to finish.**
+
+![Gitlint Dev Container Instructions](images/dev-container.png)
+
+
+After setup has finished, you should be able to just activate the virtualenv in the home dir and run the tests:
+```sh
+. ~/.venv/bin/activate
+./run_tests.sh
+```
+
+By default we have python 3.11 installed in the dev container, but you can also use [asdf](https://asdf-vm.com/)
+(preinstalled) to install additional python versions:
+
+```sh
+# Ensure ASDF overrides system python in PATH
+# You can also append this line to your ~/.bash_profile in the devcontainer to have this happen automatically on login
+source "$(brew --prefix asdf)/libexec/asdf.sh"
+
+# Install python 3.9.15
+asdf install python 3.9.15
+# List all available python versions
+asdf list all python
+# List installed python versions
+asdf list python
+```
+
+## Running tests
 ```sh
 ./run_tests.sh                       # run unit tests and print test coverage
-./run_tests.sh gitlint/tests/rules/test_body_rules.py::BodyRuleTests::test_body_missing # run a single test
+./run_tests.sh gitlint-core/gitlint/tests/rules/test_body_rules.py::BodyRuleTests::test_body_missing # run a single test
+pytest -k test_body_missing          # Alternative way to run a specific test by invoking pytest directly with a keyword expression
 ./run_tests.sh --no-coverage         # run unit tests without test coverage
 ./run_tests.sh --collect-only --no-coverage  # Only collect, don't run unit tests
 ./run_tests.sh --integration         # Run integration tests (requires that you have gitlint installed)
 ./run_tests.sh --build               # Run build tests (=build python package)
-./run_tests.sh --pep8                # pep8 checks
+./run_tests.sh --format              # format checks (black)
 ./run_tests.sh --stats               # print some code stats
 ./run_tests.sh --git                 # inception: run gitlint against itself
 ./run_tests.sh --lint                # run pylint checks
-./run_tests.sh --all                 # Run unit, integration, pep8 and gitlint checks
+./run_tests.sh --all                 # Run unit, integration, format and gitlint checks
+```
+## Formatting
+
+We use [black](https://black.readthedocs.io/en/stable/) for code formatting.
+To use it, just run black against the code you modified:
+
+```sh
+black . # format all python code
+black gitlint-core/gitlint/lint.py # format a specific file
 ```
 
-The `Vagrantfile` comes with `virtualenv`s for python 3.6, 3.7, 3.8, 3.9 and pypy3.6.
-You can easily run tests against specific python environments by using the following commands *inside* of the Vagrant VM:
+## Documentation
+We use [mkdocs](https://www.mkdocs.org/) for generating our documentation from markdown.
+
+To use it:
 ```sh
-./run_tests.sh --envs 36               # Run the unit tests against Python 3.6
-./run_tests.sh --envs 36,37,pypy36     # Run the unit tests against Python 3.6, Python 3.7 and Pypy3.6
-./run_tests.sh --envs 36,37 --pep8     # Run pep8 checks against Python 3.6 and Python 3.7 (also works for --git, --integration, --pep8, --stats and --lint.
-./run_tests.sh --envs all --all        # Run all tests against all environments
-./run_tests.sh --all-env --all         # Idem: Run all tests against all environments
+pip install -r doc-requirements.txt # install doc requirements
+mkdocs serve
 ```
 
-!!! important
-    Gitlint commits and pull requests are gated on all of our tests and checks.
+Then access the documentation website on [http://localhost:8000]().
 
 ## Packaging
 
+Gitlint consists of 2 python packages: [gitlint](https://pypi.org/project/gitlint/)
+and [gitlint-core](https://pypi.org/project/gitlint-core/).
+
+The `gitlint` package is just a wrapper package around `gitlint-core[trusted-deps]` which strictly pins gitlint
+dependencies to known working versions.
+
+There are scenarios where users (or OS package managers) may want looser dependency requirements.
+In these cases, users can just install `gitlint-core` directly (`pip install gitlint-core`).
+
+[Issue 162](https://github.com/jorisroovers/gitlint/issues/162) has all the background of how we got to the decision
+to split gitlint in 2 packages.
+
+![Gitlint package structure](images/gitlint-packages.png)
+
+### Packaging description
+
 To see the package description in HTML format
 ```sh
 pip install docutils
@@ -89,16 +143,6 @@ export LANG=en_US.UTF-8
 python setup.py --long-description | rst2html.py > output.html
 ```
 
-## Documentation
-We use [mkdocs](https://www.mkdocs.org/) for generating our documentation from markdown.
-
-To use it, do the following outside of the vagrant box (on your host machine):
-```sh
-pip install -r doc-requirements.txt # install doc requirements
-mkdocs serve
-```
-
-Then access the documentation website on your host machine on [http://localhost:8000]().
 
 ## Tools
 We keep a small set of scripts in the `tools/` directory:
@@ -110,13 +154,13 @@ tools/windows/run_tests.bat          # Windows run unit tests
 ```
 
 ## Contrib rules
-Since gitlint 0.12.0, we support [Contrib rules](../contrib_rules): community contributed rules that are part of gitlint
+Since gitlint 0.12.0, we support [Contrib rules](contrib_rules.md): community contributed rules that are part of gitlint
 itself. Thanks for considering to add a new one to gitlint!
 
 Before starting, please read all the other documentation on this page about contributing first.
 Then, we suggest taking the following approach to add a Contrib rule:
 
-1. **Write your rule as a [user-defined rule](../user_defined_rules)**. In terms of code, Contrib rules are identical to
+1. **Write your rule as a [user-defined rule](user_defined_rules.md)**. In terms of code, Contrib rules are identical to
    user-defined rules, they just happen to have their code sit within the gitlint codebase itself.
 2. **Add your user-defined rule to gitlint**. You should put your file(s) in the [gitlint/contrib/rules](https://github.com/jorisroovers/gitlint/tree/main/gitlint-core/gitlint/contrib/rules) directory.
 3. **Write unit tests**. The gitlint codebase contains [Contrib rule test files you can copy and modify](https://github.com/jorisroovers/gitlint/tree/main/gitlint-core/gitlint/tests/contrib/rules).
@@ -129,7 +173,7 @@ If you follow the steps above and follow the existing gitlint conventions wrt na
 
 In case you're looking for a slightly more formal spec, here's what gitlint requires of Contrib rules.
 
-- Since Contrib rules are really just user-defined rules that live within the gitlint code-base, all the [user-rule requirements](../user_defined_rules/#rule-requirements) also apply to Contrib rules.
+- Since Contrib rules are really just user-defined rules that live within the gitlint code-base, all the [user-rule requirements](user_defined_rules.md#rule-requirements) also apply to Contrib rules.
 - All contrib rules **must** have associated unit tests. We *sort of* enforce this by a unit test that verifies that there's a
   test file for each contrib file.
 - All contrib rules **must** have names that start with `contrib-`. This is to easily distinguish them from default gitlint rules.
@@ -137,4 +181,4 @@ In case you're looking for a slightly more formal spec, here's what gitlint requ
 - All contrib rules **must** have unique names and ids.
 - You **can** add multiple rule classes to the same file, but classes **should** be logically grouped together in a single file that implements related rules.
 - Contrib rules **should** be meaningfully different from one another. If a behavior change or tweak can be added to an existing rule by adding options, that should be considered first. However, large [god classes](https://en.wikipedia.org/wiki/God_object) that implement multiple rules in a single class should obviously also be avoided.
-- Contrib rules **should** use [options](../user_defined_rules/#options) to make rules configurable.
+- Contrib rules **should** use [options](user_defined_rules.md#options) to make rules configurable.
diff --git a/docs/demos/asciicinema.json b/docs/demos/asciicinema.json
index c6e2747..a5664c7 100644
--- a/docs/demos/asciicinema.json
+++ b/docs/demos/asciicinema.json
@@ -1448,7 +1448,7 @@
     ],
     [
       0.002767,
-      "\u001b[1;1H\u001b[93m  1 \r\n  2 \u001b[m\u001b[96m# Please enter the commit message for your changes. Lines starting\u001b[m\r\n\u001b[93m  3 \u001b[m\u001b[96m# with '#' will be ignored, and an empty message aborts the commit.\u001b[m\r\n\u001b[93m  4 \u001b[m\u001b[96m# On branch \u001b[m\u001b[38;5;224mmaster\u001b[m\r\n\u001b[93m  5 \u001b[m\u001b[96m# \u001b[m\u001b[38;5;81mChanges to be committed:\u001b[m\r\n\u001b[93m  6 \u001b[m\u001b[96m#   \u001b[m\u001b[38;5;121mnew file\u001b[m\u001b[96m: \u001b[m\u001b[95m  foo.txt\u001b[m\r\n\u001b[93m  7 \u001b[m\u001b[96m#\u001b[m\r\n\u001b[94m~                                                                                                     \u001b[9;1H~                                                                                                     \u001b[10;1H~                                                                                                     \u001b[11;1H~                                                                                                     \u001b[12;1H~                                                                                                     \u001b[13;1H~                                                                        "
+      "\u001b[1;1H\u001b[93m  1 \r\n  2 \u001b[m\u001b[96m# Please enter the commit message for your changes. Lines starting\u001b[m\r\n\u001b[93m  3 \u001b[m\u001b[96m# with '#' will be ignored, and an empty message aborts the commit.\u001b[m\r\n\u001b[93m  4 \u001b[m\u001b[96m# On branch \u001b[m\u001b[38;5;224mmain\u001b[m\r\n\u001b[93m  5 \u001b[m\u001b[96m# \u001b[m\u001b[38;5;81mChanges to be committed:\u001b[m\r\n\u001b[93m  6 \u001b[m\u001b[96m#   \u001b[m\u001b[38;5;121mnew file\u001b[m\u001b[96m: \u001b[m\u001b[95m  foo.txt\u001b[m\r\n\u001b[93m  7 \u001b[m\u001b[96m#\u001b[m\r\n\u001b[94m~                                                                                                     \u001b[9;1H~                                                                                                     \u001b[10;1H~                                                                                                     \u001b[11;1H~                                                                                                     \u001b[12;1H~                                                                                                     \u001b[13;1H~                                                                        "
     ],
     [
       0.000062,
@@ -2404,7 +2404,7 @@
     ],
     [
       0.052844,
-      "1: T3 Title has trailing punctuation (!): \"WIP: This is an patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is an patchset that I need to continue working on!\"\r\n3: B6 Body message is missing\r\n"
+      "1: T3 Title has trailing punctuation (!): \"WIP: This is a patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is a patchset that I need to continue working on!\"\r\n3: B6 Body message is missing\r\n"
     ],
     [
       0.006075,
@@ -2432,7 +2432,7 @@
     ],
     [
       0.004763,
-      "[master 4b1f92d] WIP: This is an patchset that I need to continue working on!\r\n"
+      "[main 4b1f92d] WIP: This is a patchset that I need to continue working on!\r\n"
     ],
     [
       0.001504,
@@ -3108,11 +3108,11 @@
     ],
     [
       0.050694,
-      "1: T1 Title exceeds max length (60\u003e50): \"WIP: This is an patchset that I need to continue working on!\"\r\n"
+      "1: T1 Title exceeds max length (60\u003e50): \"WIP: This is a patchset that I need to continue working on!\"\r\n"
     ],
     [
       0.000006,
-      "1: T3 Title has trailing punctuation (!): \"WIP: This is an patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is an patchset that I need to continue working on!\"\r\n3: B6 Body message is missing\r\n"
+      "1: T3 Title has trailing punctuation (!): \"WIP: This is a patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is a patchset that I need to continue working on!\"\r\n3: B6 Body message is missing\r\n"
     ],
     [
       0.005418,
@@ -3508,7 +3508,7 @@
     ],
     [
       0.050989,
-      "1: T1 Title exceeds max length (60\u003e50): \"WIP: This is an patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is an patchset that I need to continue working on!\"\r\n"
+      "1: T1 Title exceeds max length (60\u003e50): \"WIP: This is a patchset that I need to continue working on!\"\r\n1: T5 Title contains the word 'WIP' (case-insensitive): \"WIP: This is a patchset that I need to continue working on!\"\r\n"
     ],
     [
       0.000025,
@@ -3795,4 +3795,4 @@
       "exit\r\n"
     ]
   ]
-}
+}
\ No newline at end of file
diff --git a/docs/extra.css b/docs/extra.css
index 5643925..12a7663 100644
--- a/docs/extra.css
+++ b/docs/extra.css
@@ -2,3 +2,11 @@ a.toctree-l3 {
     margin-left: 10px;
     /* display: none; */
 }
+
+.wy-nav-content {
+    max-width: 1000px;
+}
+
+.document hr {
+    border-top: 1px solid #666;
+}
\ No newline at end of file
diff --git a/docs/images/dev-container.png b/docs/images/dev-container.png
new file mode 100644
index 0000000..6cac5a2
--- /dev/null
+++ b/docs/images/dev-container.png
diff --git a/docs/images/gitlint-packages.drawio.svg b/docs/images/gitlint-packages.drawio.svg
new file mode 100644
index 0000000..6098e3d
--- /dev/null
+++ b/docs/images/gitlint-packages.drawio.svg
@@ -0,0 +1,351 @@
+<svg host="65bd71144e" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="491px" height="391px" viewBox="-0.5 -0.5 491 391" content="&lt;mxfile&gt;&lt;diagram id=&quot;x7jBp0SZ1TbX-vMHKkT6&quot; name=&quot;Page-1&quot;&gt;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&lt;/diagram&gt;&lt;/mxfile&gt;">
+    <defs/>
+    <g>
+        <rect x="210" y="140" width="280" height="250" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe flex-end; width: 275px; height: 1px; padding-top: 147px; margin-left: 210px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: right;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                <b>
+                                    gitlint-core
+                                </b>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="485" y="159" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="end">
+                    gitlint-core
+                </text>
+            </switch>
+        </g>
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+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe center; width: 98px; height: 1px; padding-top: 197px; margin-left: 376px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                <i>
+                                    <font color="#ff0000">
+                                        trusted-deps
+                                    </font>
+                                </i>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="425" y="209" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    trusted-deps
+                </text>
+            </switch>
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+        <rect x="370" y="170" width="100" height="20" fill="none" stroke="none" pointer-events="all"/>
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+            <switch>
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+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 180px; margin-left: 420px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: nowrap;">
+                                <b>
+                                    extra_requires
+                                </b>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="420" y="184" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    extra_requires
+                </text>
+            </switch>
+        </g>
+        <rect x="229" y="170" width="100" height="20" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 180px; margin-left: 279px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: nowrap;">
+                                <b>
+                                    install_requires
+                                </b>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="279" y="184" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    install_requires
+                </text>
+            </switch>
+        </g>
+        <rect x="230" y="310" width="245" height="60" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 243px; height: 1px; padding-top: 340px; margin-left: 231px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                Source Code, CLI entry point, etc
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="353" y="344" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    Source Code, CLI entry point, etc
+                </text>
+            </switch>
+        </g>
+        <rect x="380" y="220" width="90" height="50" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe flex-start; width: 1px; height: 1px; padding-top: 245px; margin-left: 382px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: left;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: nowrap;">
+                                <div>
+                                    Click==8.0.3
+                                    <br/>
+                                    <span>
+                                        arrow==1.2.1
+                                        <br/>
+                                        ...
+                                    </span>
+                                </div>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="382" y="249" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px">
+                    Click==8.0.3...
+                </text>
+            </switch>
+        </g>
+        <rect x="240" y="220" width="70" height="50" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe flex-start; width: 1px; height: 1px; padding-top: 245px; margin-left: 242px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: left;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: nowrap;">
+                                <div>
+                                    Click&gt;=8
+                                    <br/>
+                                    <span>
+                                        arrow&gt;=1
+                                        <br/>
+                                        ...
+                                    </span>
+                                </div>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="242" y="249" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px">
+                    Click&gt;=8...
+                </text>
+            </switch>
+        </g>
+        <rect x="180" y="130" width="90" height="20" rx="3" ry="3" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 88px; height: 1px; padding-top: 140px; margin-left: 181px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                PyPI package
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="225" y="144" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    PyPI package
+                </text>
+            </switch>
+        </g>
+        <rect x="210" y="11" width="280" height="95" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe flex-end; width: 275px; height: 1px; padding-top: 18px; margin-left: 210px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: right;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                <b>
+                                    gitlint
+                                </b>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="485" y="30" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="end">
+                    gitlint
+                </text>
+            </switch>
+        </g>
+        <rect x="180" y="1" width="90" height="20" rx="3" ry="3" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 88px; height: 1px; padding-top: 11px; margin-left: 181px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                PyPI package
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="225" y="15" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    PyPI package
+                </text>
+            </switch>
+        </g>
+        <rect x="235" y="46" width="200" height="45" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <rect x="229" y="26" width="100" height="20" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 36px; margin-left: 279px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: nowrap;">
+                                <b>
+                                    install_requires
+                                </b>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="279" y="40" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    install_requires
+                </text>
+            </switch>
+        </g>
+        <rect x="243" y="53.5" width="195" height="30" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe flex-start; width: 193px; height: 1px; padding-top: 61px; margin-left: 245px;">
+                        <div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: left;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">
+                                gitlint-core[
+                                <i>
+                                    <font color="#ff0000">
+                                        trusted-deps
+                                    </font>
+                                </i>
+                                ]==0.17.0
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="245" y="73" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px">
+                    gitlint-core[trusted-deps]==0.17...
+                </text>
+            </switch>
+        </g>
+        <path d="M 350 80 L 350 230 Q 350 240 359.32 240 L 368.63 240" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/>
+        <path d="M 373.88 240 L 366.88 243.5 L 368.63 240 L 366.88 236.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <path d="M 100 68 L 193.63 68" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/>
+        <path d="M 198.88 68 L 191.88 71.5 L 193.63 68 L 191.88 64.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <path d="M 50 91.5 C 50 72.7 50 63.3 70 63.3 C 56.67 63.3 56.67 44.5 70 44.5 C 83.33 44.5 83.33 63.3 70 63.3 C 90 63.3 90 72.7 90 91.5 Z" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <path d="M 50 277 C 50 258.2 50 248.8 70 248.8 C 56.67 248.8 56.67 230 70 230 C 83.33 230 83.33 248.8 70 248.8 C 90 248.8 90 258.2 90 277 Z" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <rect x="20" y="100" width="100" height="30" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 98px; height: 1px; padding-top: 115px; margin-left: 21px;">
+                        <div data-drawio-colors="color: #000000; background-color: #FFFFFF; " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: normal; overflow-wrap: normal;">
+                                <span style="font-family: &quot;helvetica&quot; ; font-size: 12px ; font-weight: 400 ; letter-spacing: normal ; text-align: center ; text-indent: 0px ; text-transform: none ; word-spacing: 0px ; display: inline ; float: none">
+                                    <i>
+                                        pip install gitlint
+                                    </i>
+                                </span>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="70" y="119" fill="#000000" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    pip install gitl...
+                </text>
+            </switch>
+        </g>
+        <rect x="15" y="290" width="130" height="30" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 128px; height: 1px; padding-top: 305px; margin-left: 16px;">
+                        <div data-drawio-colors="color: #000000; background-color: #FFFFFF; " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: normal; overflow-wrap: normal;">
+                                <span style="font-family: &quot;helvetica&quot; ; font-size: 12px ; font-weight: 400 ; letter-spacing: normal ; text-align: center ; text-indent: 0px ; text-transform: none ; word-spacing: 0px ; display: inline ; float: none">
+                                    <i>
+                                        pip install gitlint-core
+                                    </i>
+                                </span>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="80" y="309" fill="#000000" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    pip install gitlint-c...
+                </text>
+            </switch>
+        </g>
+        <rect x="0" y="0" width="160" height="30" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 158px; height: 1px; padding-top: 15px; margin-left: 1px;">
+                        <div data-drawio-colors="color: #000000; background-color: #FFFFFF; " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: normal; overflow-wrap: normal;">
+                                <span style="font-family: &quot;helvetica&quot; ; font-size: 12px ; font-weight: 400 ; letter-spacing: normal ; text-indent: 0px ; text-transform: none ; word-spacing: 0px ; display: inline ; float: none">
+                                    Use strict dependencies (most users)
+                                </span>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="80" y="19" fill="#000000" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    Use strict dependencies (m...
+                </text>
+            </switch>
+        </g>
+        <rect x="0" y="180" width="160" height="30" fill="none" stroke="none" pointer-events="all"/>
+        <g transform="translate(-0.5 -0.5)">
+            <switch>
+                <foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
+                    <div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 158px; height: 1px; padding-top: 195px; margin-left: 1px;">
+                        <div data-drawio-colors="color: #000000; background-color: #FFFFFF; " style="box-sizing: border-box; font-size: 0px; text-align: center;">
+                            <div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: normal; overflow-wrap: normal;">
+                                <span style="font-family: &quot;helvetica&quot; ; font-size: 12px ; font-weight: 400 ; letter-spacing: normal ; text-indent: 0px ; text-transform: none ; word-spacing: 0px ; display: inline ; float: none">
+                                    Use loose dependencies
+                                    <br/>
+                                    (at your risk)
+                                </span>
+                            </div>
+                        </div>
+                    </div>
+                </foreignObject>
+                <text x="80" y="199" fill="#000000" font-family="Helvetica" font-size="12px" text-anchor="middle">
+                    Use loose dependencies...
+                </text>
+            </switch>
+        </g>
+        <path d="M 100 253.5 L 193.63 253.03" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/>
+        <path d="M 198.88 253.01 L 191.9 256.54 L 193.63 253.03 L 191.86 249.54 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <path d="M 210 250 L 215 250 Q 220 250 220 240 L 220 213 Q 220 203 224.07 203 L 228.13 203" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/>
+        <path d="M 233.38 203 L 226.38 206.5 L 228.13 203 L 226.38 199.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <ellipse cx="210" cy="253.5" rx="10" ry="10" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+        <path d="M 220 68 L 228.64 68.29" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/>
+        <path d="M 233.88 68.46 L 226.77 71.73 L 228.64 68.29 L 227 64.73 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/>
+        <ellipse cx="210" cy="68" rx="10" ry="10" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
+    </g>
+    <switch>
+        <g requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"/>
+        <a transform="translate(0,-5)" xlink:href="https://www.diagrams.net/doc/faq/svg-export-text-problems" target="_blank">
+            <text text-anchor="middle" font-size="10px" x="50%" y="100%">
+                Viewer does not support full SVG 1.1
+            </text>
+        </a>
+    </switch>
+</svg>
\ No newline at end of file
diff --git a/docs/images/gitlint-packages.png b/docs/images/gitlint-packages.png
new file mode 100644
index 0000000..00d3ec1
--- /dev/null
+++ b/docs/images/gitlint-packages.png
diff --git a/docs/index.md b/docs/index.md
index 398b4e5..801a16e 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -22,11 +22,11 @@ Great for use as a [commit-msg git hook](#using-gitlint-as-a-commit-msg-hook) or
  - **Easily integrated**: Gitlint is designed to work [with your own scripts or CI system](#using-gitlint-in-a-ci-environment).
  - **Sane defaults:** Many of gitlint's validations are based on
 [well-known](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html),
-[community](http://addamhardy.com/2013/06/05/good-commit-messages-and-enforcing-them-with-git-hooks.html),
+[community](https://addamhardy.com/2013-06-05-good-commit-messages-and-enforcing-them-with-git-hooks),
 [standards](http://chris.beams.io/posts/git-commit/), others are based on checks that we've found
 useful throughout the years.
  - **Easily configurable:** Gitlint has sane defaults, but [you can also easily customize it to your own liking](configuration.md).
- - **Community contributed rules**: Conventions that are common but not universal [can be selectively enabled](contrib_rules).
+ - **Community contributed rules**: Conventions that are common but not universal [can be selectively enabled](contrib_rules.md).
  - **User-defined rules:** Want to do more then what gitlint offers out of the box? Write your own [user defined rules](user_defined_rules.md).
  - **Full unicode support:** Lint your Russian, Chinese or Emoji commit messages with ease!
  - **Production-ready:** Gitlint checks a lot of the boxes you're looking for: actively maintained, high unit test coverage, integration tests,
@@ -38,6 +38,10 @@ useful throughout the years.
 # Pip is recommended to install the latest version
 pip install gitlint
 
+# Alternative: by default, gitlint is installed with pinned dependencies.
+# To install gitlint with looser dependency requirements, only install gitlint-core.
+pip install gitlint-core
+
 # Community maintained packages:
 brew install gitlint       # Homebrew (macOS)
 sudo port install gitlint  # Macports (macOS)
@@ -81,6 +85,19 @@ $ cat examples/commit-message-2 | gitlint
 !!! note
     The returned exit code equals the number of errors found. [Some exit codes are special](index.md#exit-codes).
 
+### Shell completion
+
+```sh
+# Bash: add to ~/.bashrc
+eval "$(_GITLINT_COMPLETE=bash_source gitlint)"
+
+# Zsh: add to ~/.zshrc
+eval "$(_GITLINT_COMPLETE=zsh_source gitlint)"
+
+# Fish: add to ~/.config/fish/completions/foo-bar.fish
+eval (env _GITLINT_COMPLETE=fish_source gitlint)
+```
+
 ## Configuration
 
 For in-depth documentation of general and rule-specific configuration options, have a look at the [Configuration](configuration.md) and [Rules](rules.md) pages.
@@ -93,7 +110,7 @@ Short example `.gitlint` file ([full reference](configuration.md)):
 # their id or by their full name
 ignore=body-is-missing,T3
 
-# Ignore any data send to gitlint via stdin
+# Ignore any data sent to gitlint via stdin
 ignore-stdin=true
 
 # Configure title-max-length rule, set title length to 80 (72 = default)
@@ -136,7 +153,8 @@ Options:
                            (e.g.: -c T1.line-length=80). Flag can be
                            used multiple times to set multiple config values.
   --commit TEXT            Hash (SHA) of specific commit to lint.
-  --commits TEXT           The range of commits to lint. [default: HEAD]
+  --commits TEXT           The range of commits (refspec or comma-separated
+                           hashes) to lint. [default: HEAD]
   -e, --extra-path PATH    Path to a directory or python module with extra
                            user-defined rules
   --ignore TEXT            Ignore rules (comma-separated by id or name).
@@ -145,8 +163,9 @@ Options:
   --msg-filename FILENAME  Path to a file containing a commit-msg.
   --ignore-stdin           Ignore any stdin data. Useful for running in CI
                            server.
-  --staged                 Read staged commit meta-info from the local
-                           repository.
+  --staged                 Attempt smart guesses about meta info (like
+                           author name, email, branch, changed files, etc)
+                           for staged commits.
   --fail-without-commits   Hard fail when the target commit range is empty.
   -v, --verbose            Verbosity, more v's for more verbose output
                            (e.g.: -v, -vv, -vvv). [default: -vvv]
@@ -218,7 +237,7 @@ In case you want to change gitlint's behavior, you should either use a `.gitlint
 your `.pre-commit-config.yaml` file like so:
 ```yaml
 -   repo: https://github.com/jorisroovers/gitlint
-    rev:  # Fill in a tag / sha here
+    rev:  # Fill in a tag / sha here (e.g. v0.18.0)
     hooks:
     -   id: gitlint
         args: [--contrib=CT1, --msg-filename]
@@ -229,6 +248,36 @@ your `.pre-commit-config.yaml` file like so:
     You need to add `--msg-filename` at the end of your custom `args` list as the gitlint-hook will fail otherwise.
 
 
+### gitlint and pre-commit in CI
+gitlint also supports a `gitlint-ci` pre-commit hook that can be used in CI environments.
+
+Configure it like so:
+```yaml
+-   repo: https://github.com/jorisroovers/gitlint
+    rev:  # insert ref, e.g. v0.18.0
+    hooks:
+    -   id: gitlint    # this is the regular commit-msg hook
+    -   id: gitlint-ci # hook for CI environments
+```
+
+And invoke it in your CI environment like this:
+
+```sh
+pre-commit run --hook-stage manual gitlint-ci
+```
+
+By default this will only lint the latest commit.
+If you want to lint more commits you can modify the `gitlint-ci` hook like so:
+
+```yaml
+-   repo: https://github.com/jorisroovers/gitlint
+    rev:  v0.17.0
+    hooks:
+    -   id: gitlint
+    -   id: gitlint-ci
+        args: [--debug, --commits, mybranch] # enable debug mode, lint all commits in mybranch
+```
+
 ## Using gitlint in a CI environment
 By default, when just running `gitlint` without additional parameters, gitlint lints the last commit in the current
 working directory.
@@ -248,33 +297,48 @@ git log -1 --pretty=%B 62c0519 | gitlint
 Note that gitlint requires that you specify `--pretty=%B` (=only print the log message, not the metadata),
 future versions of gitlint might fix this and not require the `--pretty` argument.
 
-## Linting specific commits
+## Linting specific commits or branches
 
-Gitlint allows users to lint a specific commit:
+Gitlint can lint specific commits using `--commit`:
 ```sh
 gitlint --commit 019cf40580a471a3958d3c346aa8bfd265fe5e16
-gitlint --commit 019cf40 # short SHAs work too
+gitlint --commit 019cf40  # short SHAs work too
+gitlint --commit HEAD~2   # as do special references
+gitlint --commit mybranch # lint latest commit on a branch 
 ```
 
-You can also lint multiple commits at once like so:
+You can also lint multiple commits using `--commits` (plural):
 
 ```sh
 # Lint a specific commit range:
 gitlint --commits "019cf40...d6bc75a"
-# You can also use git's special references:
+# Lint all commits on a branch
+gitlint --commits mybranch
+# Lint all commits that are different between a branch and your main branch
+gitlint --commits "main..mybranch"
+# Use git's special references
 gitlint --commits "origin..HEAD"
+
+# You can also pass multiple, comma separated commit hashes:
+gitlint --commits 019cf40,c50eb150,d6bc75a
+# These can include special references as well
+gitlint --commits HEAD~1,mybranch-name,origin/main,d6bc75a
 ```
 
 The `--commits` flag takes a **single** refspec argument or commit range. Basically, any range that is understood
 by [git rev-list](https://git-scm.com/docs/git-rev-list) as a single argument will work.
 
+Alternatively, you can pass `--commits` a comma-separated list of commit hashes (both short and full-length SHAs work,
+as well as special references such as `HEAD` and branch names).
+Gitlint will treat these as pointers to **single** commits and lint these in the order you passed.
+
 For cases where the `--commits` option doesn't provide the flexibility you need, you can always use a simple shell
 script to lint an arbitrary set of commits, like shown in the example below.
 
 ```sh
 #!/bin/sh
 
-for commit in $(git rev-list master); do
+for commit in $(git rev-list my-branch); do
     echo "Commit $commit"
     gitlint --commit $commit
     echo "--------"
@@ -283,14 +347,14 @@ done
 
 !!! note
     One downside to this approach is that you invoke gitlint once per commit vs. once per set of commits.
-    This means you'll incur the gitlint startup time once per commit, making this approach rather slow if you want to
+    This means you'll incur the gitlint startup time once per commit, making it rather slow if you want to
     lint a large set of commits. Always use `--commits` if you can to avoid this performance penalty.
 
 
 ## Merge, fixup, squash and revert commits
-_Introduced in gitlint v0.7.0 (merge), v0.9.0 (fixup, squash) and v0.13.0 (revert)_
+_Introduced in gitlint v0.7.0 (merge), v0.9.0 (fixup, squash), v0.13.0 (revert) and v0.18.0 (fixup=amend)_
 
-**Gitlint ignores merge, revert, fixup and squash commits by default.**
+**Gitlint ignores merge, revert, fixup, and squash commits by default.**
 
 For merge and revert commits, the rationale for ignoring them is
 that most users keep git's default messages for these commits (i.e *Merge/Revert "[original commit message]"*).
@@ -300,14 +364,14 @@ For example, a common case is that *"Merge:"* being auto-prepended triggers a
 [title-max-length](rules.md#t1-title-max-length) violation. Most users don't want this, so we disable linting
 on Merge and Revert commits by default.
 
-For [squash](https://git-scm.com/docs/git-commit#git-commit---squashltcommitgt) and [fixup](https://git-scm.com/docs/git-commit#git-commit---fixupltcommitgt) commits, the rationale is that these are temporary
+For [squash](https://git-scm.com/docs/git-commit#git-commit---squashltcommitgt) and [fixup](https://git-scm.com/docs/git-commit#git-commit---fixupltcommitgt) (including [fixup=amend](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---fixupamendrewordltcommitgt)) commits, the rationale is that these are temporary
 commits that will be squashed into a different commit, and hence the commit messages for these commits are very
-short-lived and not intended to make it into the final commit history. In addition, by prepending *"fixup!"* or
-*"squash!"* to your commit message, certain gitlint rules might be violated
+short-lived and not intended to make it into the final commit history. In addition, by prepending *"fixup!"*,
+*"amend!"* or *"squash!"* to your commit message, certain gitlint rules might be violated
 (e.g. [title-max-length](rules.md#t1-title-max-length)) which is often undesirable.
 
 In case you *do* want to lint these commit messages, you can disable this behavior by setting the
-general `ignore-merge-commits`, `ignore-revert-commits`,  `ignore-fixup-commits` or
+general `ignore-merge-commits`, `ignore-revert-commits`,  `ignore-fixup-commits`, `ignore-fixup-amend-commits` or
 `ignore-squash-commits` option to `false`
 [using one of the various ways to configure gitlint](configuration.md).
 
@@ -374,7 +438,7 @@ additional unique identifier (i.e. the rule *name*) during configuration.
     For example, by defining 2 `body-max-line-length` rules with different `line-length` options, you obviously create
     a conflicting situation. Gitlint does not do any resolution of such conflicts, it's up to you to make sure
     any configuration is non-conflicting. So caution advised!
-    
+
 Defining a named rule is easy, for example using your `.gitlint` file:
 
 ```ini
@@ -400,7 +464,7 @@ When executing gitlint, you will see the violations from the default `title-must
 the violations caused by the additional Named Rules.
 
 ```sh
-$ gitlint 
+$ gitlint
 1: T5 Title contains the word 'WIP' (case-insensitive): "WIP: foo wonderwoman hur bar"
 1: T5:This-Can_Be*Whatever$YouWant Title contains the word 'wonderwoman' (case-insensitive): "WIP: foo wonderwoman hur bar"
 1: T5:extra-words Title contains the word 'foo' (case-insensitive): "WIP: foo wonderwoman hur bar"
@@ -431,8 +495,8 @@ of violations counted by the exit code is 252. Note that gitlint does not have a
 it can detect, it will just always return with exit code 252 when the number of violations is greater than or equal
 to 252.
 
-Exit Code  | Description
------------|------------------------------------------------------------
-253        | Wrong invocation of the `gitlint` command.
-254        | Something went wrong when invoking git.
-255        | Invalid gitlint configuration
+| Exit Code | Description                                |
+| --------- | ------------------------------------------ |
+| 253       | Wrong invocation of the `gitlint` command. |
+| 254       | Something went wrong when invoking git.    |
+| 255       | Invalid gitlint configuration              |
diff --git a/docs/rules.md b/docs/rules.md
index eb4b65e..a992f26 100644
--- a/docs/rules.md
+++ b/docs/rules.md
@@ -8,43 +8,43 @@ In addition, you can also [write your own user-defined rule](user_defined_rules.
 what you're looking for.
 
 
-ID    | Name                        | gitlint version   | Description
-------|-----------------------------|-------------------|-------------------------------------------
-T1    | title-max-length            | >= 0.1.0          | Title length must be &lt; 72 chars.
-T2    | title-trailing-whitespace   | >= 0.1.0          | Title cannot have trailing whitespace (space or tab)
-T3    | title-trailing-punctuation  | >= 0.1.0          | Title cannot have trailing punctuation (?:!.,;)
-T4    | title-hard-tab              | >= 0.1.0          | Title cannot contain hard tab characters (\t)
-T5    | title-must-not-contain-word | >= 0.1.0          | Title cannot contain certain words (default: "WIP")
-T6    | title-leading-whitespace    | >= 0.4.0          | Title cannot have leading whitespace (space or tab)
-T7    | title-match-regex           | >= 0.5.0          | Title must match a given regex (default: None)
-T8    | title-min-length            | >= 0.14.0         | Title length must be &gt; 5 chars.
-B1    | body-max-line-length        | >= 0.1.0          | Lines in the body must be &lt; 80 chars
-B2    | body-trailing-whitespace    | >= 0.1.0          | Body cannot have trailing whitespace (space or tab)
-B3    | body-hard-tab               | >= 0.1.0          | Body cannot contain hard tab characters (\t)
-B4    | body-first-line-empty       | >= 0.1.0          | First line of the body (second line of commit message) must be empty
-B5    | body-min-length             | >= 0.4.0          | Body length must be at least 20 characters
-B6    | body-is-missing             | >= 0.4.0          | Body message must be specified
-B7    | body-changed-file-mention   | >= 0.4.0          | Body must contain references to certain files if those files are changed in the last commit
-B8    | body-match-regex            | >= 0.14.0         | Title must match a given regex (default: None)
-M1    | author-valid-email          | >= 0.9.0          | Author email address must be a valid email address
-I1    | ignore-by-title             | >= 0.10.0         | Ignore a commit based on matching its title
-I2    | ignore-by-body              | >= 0.10.0         | Ignore a commit based on matching its body
-I3    | ignore-body-lines           | >= 0.14.0         | Ignore certain lines in a commit body that match a regex
-I4    | ignore-by-author-name       | >= 0.16.0         | Ignore a commit based on matching its author name
+| ID  | Name                        | gitlint version | Description                                                                                 |
+| --- | --------------------------- | --------------- | ------------------------------------------------------------------------------------------- |
+| T1  | title-max-length            | >= 0.1.0        | Title length must be &lt;= 72 chars.                                                        |
+| T2  | title-trailing-whitespace   | >= 0.1.0        | Title cannot have trailing whitespace (space or tab)                                        |
+| T3  | title-trailing-punctuation  | >= 0.1.0        | Title cannot have trailing punctuation (?:!.,;)                                             |
+| T4  | title-hard-tab              | >= 0.1.0        | Title cannot contain hard tab characters (\t)                                               |
+| T5  | title-must-not-contain-word | >= 0.1.0        | Title cannot contain certain words (default: "WIP")                                         |
+| T6  | title-leading-whitespace    | >= 0.4.0        | Title cannot have leading whitespace (space or tab)                                         |
+| T7  | title-match-regex           | >= 0.5.0        | Title must match a given regex (default: None)                                              |
+| T8  | title-min-length            | >= 0.14.0       | Title length must be &gt;= 5 chars.                                                         |
+| B1  | body-max-line-length        | >= 0.1.0        | Lines in the body must be &lt;= 80 chars                                                    |
+| B2  | body-trailing-whitespace    | >= 0.1.0        | Body cannot have trailing whitespace (space or tab)                                         |
+| B3  | body-hard-tab               | >= 0.1.0        | Body cannot contain hard tab characters (\t)                                                |
+| B4  | body-first-line-empty       | >= 0.1.0        | First line of the body (second line of commit message) must be empty                        |
+| B5  | body-min-length             | >= 0.4.0        | Body length must be at least 20 characters                                                  |
+| B6  | body-is-missing             | >= 0.4.0        | Body message must be specified                                                              |
+| B7  | body-changed-file-mention   | >= 0.4.0        | Body must contain references to certain files if those files are changed in the last commit |
+| B8  | body-match-regex            | >= 0.14.0       | Body must match a given regex (default: None)                                               |
+| M1  | author-valid-email          | >= 0.9.0        | Author email address must be a valid email address                                          |
+| I1  | ignore-by-title             | >= 0.10.0       | Ignore a commit based on matching its title                                                 |
+| I2  | ignore-by-body              | >= 0.10.0       | Ignore a commit based on matching its body                                                  |
+| I3  | ignore-body-lines           | >= 0.14.0       | Ignore certain lines in a commit body that match a regex                                    |
+| I4  | ignore-by-author-name       | >= 0.16.0       | Ignore a commit based on matching its author name                                           |
 
 
 
 ## T1: title-max-length
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T1    | title-max-length            | >= 0.1          | Title length must be &lt; 72 chars.
+| ID  | Name             | gitlint version | Description                          |
+| --- | ---------------- | --------------- | ------------------------------------ |
+| T1  | title-max-length | >= 0.1          | Title length must be &lt;= 72 chars. |
 
 ### Options
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-line-length    | >= 0.2          | 72      |  Maximum allowed title length
+| Name        | gitlint version | Default | Description                  |
+| ----------- | --------------- | ------- | ---------------------------- |
+| line-length | >= 0.2          | 72      | Maximum allowed title length |
 
 ### Examples
 
@@ -59,39 +59,43 @@ line-length=72
 [title-max-length]
 line-length=120
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## T2: title-trailing-whitespace
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T2    | title-trailing-whitespace   | >= 0.1          | Title cannot have trailing whitespace (space or tab)
+| ID  | Name                      | gitlint version | Description                                          |
+| --- | ------------------------- | --------------- | ---------------------------------------------------- |
+| T2  | title-trailing-whitespace | >= 0.1          | Title cannot have trailing whitespace (space or tab) |
 
+------------------------------------------------------------------------------------------------------------------------
 
 ## T3: title-trailing-punctuation
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T3    | title-trailing-punctuation  | >= 0.1          | Title cannot have trailing punctuation (?:!.,;)
+| ID  | Name                       | gitlint version | Description                                     |
+| --- | -------------------------- | --------------- | ----------------------------------------------- |
+| T3  | title-trailing-punctuation | >= 0.1          | Title cannot have trailing punctuation (?:!.,;) |
 
+------------------------------------------------------------------------------------------------------------------------
 
 ## T4: title-hard-tab
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T4    | title-hard-tab              | >= 0.1          | Title cannot contain hard tab characters (\t)
+| ID  | Name           | gitlint version | Description                                   |
+| --- | -------------- | --------------- | --------------------------------------------- |
+| T4  | title-hard-tab | >= 0.1          | Title cannot contain hard tab characters (\t) |
 
+------------------------------------------------------------------------------------------------------------------------
 
 ## T5: title-must-not-contain-word
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T5    | title-must-not-contain-word | >= 0.1          | Title cannot contain certain words (default: "WIP")
+| ID  | Name                        | gitlint version | Description                                         |
+| --- | --------------------------- | --------------- | --------------------------------------------------- |
+| T5  | title-must-not-contain-word | >= 0.1          | Title cannot contain certain words (default: "WIP") |
 
 ### Options
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-words          | >= 0.3          | WIP     | Comma-separated list of words that should not be used in the title. Matching is case insensitive
+| Name  | gitlint version | Default | Description                                                                                      |
+| ----- | --------------- | ------- | ------------------------------------------------------------------------------------------------ |
+| words | >= 0.3          | WIP     | Comma-separated list of words that should not be used in the title. Matching is case insensitive |
 
 ### Examples
 
@@ -102,25 +106,28 @@ words          | >= 0.3          | WIP     | Comma-separated list of words that
 [title-must-not-contain-word]
 words=crap,darn,damn
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## T6: title-leading-whitespace
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T6    | title-leading-whitespace    | >= 0.4          | Title cannot have leading whitespace (space or tab)
+| ID  | Name                     | gitlint version | Description                                         |
+| --- | ------------------------ | --------------- | --------------------------------------------------- |
+| T6  | title-leading-whitespace | >= 0.4          | Title cannot have leading whitespace (space or tab) |
+
+------------------------------------------------------------------------------------------------------------------------
 
 ## T7: title-match-regex
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T7    | title-match-regex           | >= 0.5          | Title must match a given regex (default: .*)
+| ID  | Name              | gitlint version | Description                                  |
+| --- | ----------------- | --------------- | -------------------------------------------- |
+| T7  | title-match-regex | >= 0.5          | Title must match a given regex (default: .*) |
 
 
 ### Options
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-regex          | >= 0.5          | .*      | [Python regex](https://docs.python.org/library/re.html) that the title should match.
+| Name  | gitlint version | Default | Description                                                                          |
+| ----- | --------------- | ------- | ------------------------------------------------------------------------------------ |
+| regex | >= 0.5          | .*      | [Python regex](https://docs.python.org/library/re.html) that the title should match. |
 
 ### Examples
 
@@ -131,19 +138,20 @@ regex          | >= 0.5          | .*      | [Python regex](https://docs.python.
 [title-match-regex]
 regex=^US[1-9][0-9]*
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## T8: title-min-length ##
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-T1    | title-min-length            | >=              | Title length must be &gt; 5 chars.
+| ID  | Name             | gitlint version | Description                         |
+| --- | ---------------- | --------------- | ----------------------------------- |
+| T8  | title-min-length | >= 0.14.0       | Title length must be &gt;= 5 chars. |
 
 
 ### Options
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-min-length     | >= 0.14.0       | 5       |  Minimum required title length
+| Name       | gitlint version | Default | Description                   |
+| ---------- | --------------- | ------- | ----------------------------- |
+| min-length | >= 0.14.0       | 5       | Minimum required title length |
 
 ### Examples
 
@@ -154,18 +162,19 @@ min-length     | >= 0.14.0       | 5       |  Minimum required title length
 [title-min-length]
 min-length=3
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## B1: body-max-line-length
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B1    | body-max-line-length        | >= 0.1          | Lines in the body must be &lt; 80 chars
+| ID  | Name                 | gitlint version | Description                              |
+| --- | -------------------- | --------------- | ---------------------------------------- |
+| B1  | body-max-line-length | >= 0.1          | Lines in the body must be &lt;= 80 chars |
 
 ### Options
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-line-length    | >= 0.2          | 80      |  Maximum allowed line length in the commit message body
+| Name        | gitlint version | Default | Description                                            |
+| ----------- | --------------- | ------- | ------------------------------------------------------ |
+| line-length | >= 0.2          | 80      | Maximum allowed line length in the commit message body |
 
 ### Examples
 
@@ -180,38 +189,43 @@ line-length=120
 [body-max-line-length]
 line-length=72
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## B2: body-trailing-whitespace
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B2    | body-trailing-whitespace    | >= 0.1          | Body cannot have trailing whitespace (space or tab)
+| ID  | Name                     | gitlint version | Description                                         |
+| --- | ------------------------ | --------------- | --------------------------------------------------- |
+| B2  | body-trailing-whitespace | >= 0.1          | Body cannot have trailing whitespace (space or tab) |
 
+------------------------------------------------------------------------------------------------------------------------
 
 ## B3: body-hard-tab
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B3    | body-hard-tab               | >= 0.1          | Body cannot contain hard tab characters (\t)
+| ID  | Name          | gitlint version | Description                                  |
+| --- | ------------- | --------------- | -------------------------------------------- |
+| B3  | body-hard-tab | >= 0.1          | Body cannot contain hard tab characters (\t) |
 
+------------------------------------------------------------------------------------------------------------------------
 
 ## B4: body-first-line-empty
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B4    | body-first-line-empty       | >= 0.1          | First line of the body (second line of commit message) must be empty
+| ID  | Name                  | gitlint version | Description                                                          |
+| --- | --------------------- | --------------- | -------------------------------------------------------------------- |
+| B4  | body-first-line-empty | >= 0.1          | First line of the body (second line of commit message) must be empty |
+
+------------------------------------------------------------------------------------------------------------------------
 
 ## B5: body-min-length
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B5    | body-min-length             | >= 0.4          | Body length must be at least 20 characters. In versions >= 0.8.0, gitlint will not count newline characters.
+| ID  | Name            | gitlint version | Description                                                                                                  |
+| --- | --------------- | --------------- | ------------------------------------------------------------------------------------------------------------ |
+| B5  | body-min-length | >= 0.4          | Body length must be at least 20 characters. In versions >= 0.8.0, gitlint will not count newline characters. |
 
 ### Options ###
 
-Name           | gitlint version | Default | Description
----------------|-----------------|---------|----------------------------------
-min-length     | >= 0.4          | 20      |  Minimum number of required characters in body
+| Name       | gitlint version | Default | Description                                   |
+| ---------- | --------------- | ------- | --------------------------------------------- |
+| min-length | >= 0.4          | 20      | Minimum number of required characters in body |
 
 ### Examples
 
@@ -226,31 +240,34 @@ min-length=5
 [body-min-length]
 min-length=100
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## B6: body-is-missing
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B6    | body-is-missing             | >= 0.4          | Body message must be specified
+| ID  | Name            | gitlint version | Description                    |
+| --- | --------------- | --------------- | ------------------------------ |
+| B6  | body-is-missing | >= 0.4          | Body message must be specified |
 
 
 ### Options
 
-Name                  | gitlint version | Default   | Description
-----------------------|-----------------|-----------|----------------------------------
-ignore-merge-commits  | >= 0.4          | true      |  Whether this rule should be ignored during merge commits. Allowed values: true,false.
+| Name                 | gitlint version | Default | Description                                                                           |
+| -------------------- | --------------- | ------- | ------------------------------------------------------------------------------------- |
+| ignore-merge-commits | >= 0.4          | true    | Whether this rule should be ignored during merge commits. Allowed values: true,false. |
+
+------------------------------------------------------------------------------------------------------------------------
 
 ## B7: body-changed-file-mention
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B7    | body-changed-file-mention   | >= 0.4          | Body must contain references to certain files if those files are changed in the last commit
+| ID  | Name                      | gitlint version | Description                                                                                 |
+| --- | ------------------------- | --------------- | ------------------------------------------------------------------------------------------- |
+| B7  | body-changed-file-mention | >= 0.4          | Body must contain references to certain files if those files are changed in the last commit |
 
 ### Options
 
-Name                  | gitlint version | Default      | Description
-----------------------|-----------------|--------------|----------------------------------
-files                 | >= 0.4          | (empty)      |  Comma-separated list of files that need to an explicit mention in the commit message in case they are changed.
+| Name  | gitlint version | Default | Description                                                                                                    |
+| ----- | --------------- | ------- | -------------------------------------------------------------------------------------------------------------- |
+| files | >= 0.4          | (empty) | Comma-separated list of files that need to an explicit mention in the commit message in case they are changed. |
 
 ### Examples
 
@@ -262,18 +279,19 @@ files                 | >= 0.4          | (empty)      |  Comma-separated list o
 [body-changed-file-mention]
 files=generated.xml,secrets.txt,private-key.pem
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## B8: body-match-regex
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-B8    | body-match-regex            | >= 0.14         | Body must match a given regex
+| ID  | Name             | gitlint version | Description                   |
+| --- | ---------------- | --------------- | ----------------------------- |
+| B8  | body-match-regex | >= 0.14         | Body must match a given regex |
 
 ### Options
 
-Name                  | gitlint version | Default      | Description
-----------------------|-----------------|--------------|----------------------------------
-regex                 | >= 0.14         | None         |  [Python regex](https://docs.python.org/library/re.html) that the title should match.
+| Name  | gitlint version | Default | Description                                                                         |
+| ----- | --------------- | ------- | ----------------------------------------------------------------------------------- |
+| regex | >= 0.14         | None    | [Python regex](https://docs.python.org/library/re.html) that the body should match. |
 
 ### Examples
 
@@ -288,12 +306,13 @@ regex=Reviewed-By:(.*)$
 [body-match-regex]
 regex=(*.)Foo(.*)
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## M1: author-valid-email
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-M1    |  author-valid-email         | >= 0.8.3        | Author email address must be a valid email address
+| ID  | Name               | gitlint version | Description                                        |
+| --- | ------------------ | --------------- | -------------------------------------------------- |
+| M1  | author-valid-email | >= 0.8.3        | Author email address must be a valid email address |
 
 !!! note
     Email addresses are [notoriously hard to validate and the official email valid spec is often too loose for any real world application](http://stackoverflow.com/a/201378/381010).
@@ -303,9 +322,9 @@ M1    |  author-valid-email         | >= 0.8.3        | Author email address mus
 
 ### Options
 
-Name                  | gitlint version   | Default                      | Description
-----------------------|-------------------|------------------------------|----------------------------------
-regex                 | >= 0.9.0          | `[^@ ]+@[^@ ]+\.[^@ ]+`  |  [Python regex](https://docs.python.org/library/re.html) the commit author email address is matched against
+| Name  | gitlint version | Default                 | Description                                                                                                |
+| ----- | --------------- | ----------------------- | ---------------------------------------------------------------------------------------------------------- |
+| regex | >= 0.9.0        | `[^@ ]+@[^@ ]+\.[^@ ]+` | [Python regex](https://docs.python.org/library/re.html) the commit author email address is matched against |
 
 
 ### Examples
@@ -317,20 +336,21 @@ regex                 | >= 0.9.0          | `[^@ ]+@[^@ ]+\.[^@ ]+`  |  [Python
 [author-valid-email]
 regex=[^@]+@foo.com
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## I1: ignore-by-title
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-I1    |  ignore-by-title            | >= 0.10.0       | Ignore a commit based on matching its title.
+| ID  | Name            | gitlint version | Description                                  |
+| --- | --------------- | --------------- | -------------------------------------------- |
+| I1  | ignore-by-title | >= 0.10.0       | Ignore a commit based on matching its title. |
 
 
 ### Options
 
-Name                  | gitlint version   | Default                      | Description
-----------------------|-------------------|------------------------------|----------------------------------
-regex                 | >= 0.10.0         | None                         |  [Python regex](https://docs.python.org/library/re.html) to match against commit title. On match, the commit will be ignored.
-ignore                | >= 0.10.0         | all                          |  Comma-separated list of rule names or ids to ignore when this rule is matched.
+| Name   | gitlint version | Default | Description                                                                                                                  |
+| ------ | --------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------- |
+| regex  | >= 0.10.0       | None    | [Python regex](https://docs.python.org/library/re.html) to match against commit title. On match, the commit will be ignored. |
+| ignore | >= 0.10.0       | all     | Comma-separated list of rule names or ids to ignore when this rule is matched.                                               |
 
 ### Examples
 
@@ -345,20 +365,21 @@ ignore=title-max-length,body-min-length
 # ignore all rules by setting ignore to 'all'
 # ignore=all
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## I2: ignore-by-body
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-I2    |  ignore-by-body             | >= 0.10.0       | Ignore a commit based on matching its body.
+| ID  | Name           | gitlint version | Description                                 |
+| --- | -------------- | --------------- | ------------------------------------------- |
+| I2  | ignore-by-body | >= 0.10.0       | Ignore a commit based on matching its body. |
 
 
 ### Options
 
-Name                  | gitlint version   | Default                      | Description
-----------------------|-------------------|------------------------------|----------------------------------
-regex                 | >= 0.10.0         | None                         |  [Python regex](https://docs.python.org/library/re.html) to match against each line of the body. On match, the commit will be ignored.
-ignore                | >= 0.10.0         | all                          |  Comma-separated list of rule names or ids to ignore when this rule is matched.
+| Name   | gitlint version | Default | Description                                                                                                                           |
+| ------ | --------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------- |
+| regex  | >= 0.10.0       | None    | [Python regex](https://docs.python.org/library/re.html) to match against each line of the body. On match, the commit will be ignored. |
+| ignore | >= 0.10.0       | all     | Comma-separated list of rule names or ids to ignore when this rule is matched.                                                        |
 
 ### Examples
 
@@ -376,19 +397,20 @@ ignore=all
 regex=(.*)release(.*)
 ignore=T1,body-min-length,B6
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## I3: ignore-body-lines
 
-ID    | Name                        | gitlint version | Description
-------|-----------------------------|-----------------|-------------------------------------------
-I3    |  ignore-body-lines          | >= 0.14.0    | Ignore certain lines in a commit body that match a regex.
+| ID  | Name              | gitlint version | Description                                               |
+| --- | ----------------- | --------------- | --------------------------------------------------------- |
+| I3  | ignore-body-lines | >= 0.14.0       | Ignore certain lines in a commit body that match a regex. |
 
 
 ### Options
 
-Name                  | gitlint version   | Default                      | Description
-----------------------|-------------------|------------------------------|----------------------------------
-regex                 | >= 0.14.0         | None                         |  [Python regex](https://docs.python.org/library/re.html) to match against each line of the body. On match, that line will be ignored by gitlint (the rest of the body will still be linted).
+| Name  | gitlint version | Default | Description                                                                                                                                                                                 |
+| ----- | --------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| regex | >= 0.14.0       | None    | [Python regex](https://docs.python.org/library/re.html) to match against each line of the body. On match, that line will be ignored by gitlint (the rest of the body will still be linted). |
 
 ### Examples
 
@@ -407,19 +429,20 @@ regex=(^Co-Authored-By)|(^Signed-off-by)
 [ignore-body-lines]
 regex=(.*)foobar(.*)
 ```
+------------------------------------------------------------------------------------------------------------------------
 
 ## I4: ignore-by-author-name
 
-ID    | Name                      | gitlint version | Description
-------|---------------------------|-----------------|-------------------------------------------
-I4    |  ignore-by-author-name    | >= 0.16.0       | Ignore a commit based on matching its author name.
+| ID  | Name                  | gitlint version | Description                                        |
+| --- | --------------------- | --------------- | -------------------------------------------------- |
+| I4  | ignore-by-author-name | >= 0.16.0       | Ignore a commit based on matching its author name. |
 
 ### Options
 
-Name                  | gitlint version   | Default                      | Description
-----------------------|-------------------|------------------------------|----------------------------------
-regex                 | >= 0.16.0         | None                         |  [Python regex](https://docs.python.org/library/re.html) to match against the commit author name. On match, the commit will be ignored.
-ignore                | >= 0.16.0         | all                          |  Comma-separated list of rule names or ids to ignore when this rule is matched.
+| Name   | gitlint version | Default | Description                                                                                                                            |
+| ------ | --------------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------- |
+| regex  | >= 0.16.0       | None    | [Python regex](https://docs.python.org/library/re.html) to match against the commit author name. On match, the commit will be ignored. |
+| ignore | >= 0.16.0       | all     | Comma-separated list of rule names or ids to ignore when this rule is matched.                                                         |
 
 ### Examples
 
@@ -435,4 +458,4 @@ regex=dependabot
 [ignore-by-author-name]
 regex=(.*)\[bot\](.*)
 ignore=T1,body-min-length,B6
-```
\ No newline at end of file
+```
diff --git a/docs/user_defined_rules.md b/docs/user_defined_rules.md
index f58dcc7..db21809 100644
--- a/docs/user_defined_rules.md
+++ b/docs/user_defined_rules.md
@@ -179,27 +179,33 @@ Both `CommitRule`s and `LineRule`s take a `commit` object in their `validate(...
 The table below outlines the various attributes of that commit object that can be used during validation.
 
 
-Property                       | Type           | Description
--------------------------------| ---------------|-------------------
-commit.message                 | object         | Python object representing the commit message
-commit.message.original        | string         | Original commit message as returned by git
-commit.message.full            | string         | Full commit message, with comments (lines starting with #) removed.
-commit.message.title           | string         | Title/subject of the commit message: the first line
-commit.message.body            | string[]       | List of lines in the body of the commit message (i.e. starting from the second line)
-commit.author_name             | string         | Name of the author, result of `git log --pretty=%aN`
-commit.author_email            | string         | Email of the author, result of `git log --pretty=%aE`
-commit.date                    | datetime       | Python `datetime` object representing the time of commit
-commit.is_merge_commit         | boolean        | Boolean indicating whether the commit is a merge commit or not.
-commit.is_revert_commit        | boolean        | Boolean indicating whether the commit is a revert commit or not.
-commit.is_fixup_commit         | boolean        | Boolean indicating whether the commit is a fixup commit or not.
-commit.is_squash_commit        | boolean        | Boolean indicating whether the commit is a squash commit or not.
-commit.parents                 | string[]       | List of parent commit `sha`s (only for merge commits).
-commit.changed_files           | string[]       | List of files changed in the commit (relative paths).
-commit.branches                | string[]       | List of branch names the commit is part of
-commit.context                 | object         | Object pointing to the bigger git context that the commit is part of
-commit.context.current_branch  | string         | Name of the currently active branch (of local repo)
-commit.context.repository_path | string         | Absolute path pointing to the git repository being linted
-commit.context.commits         | object[]       | List of commits gitlint is acting on, NOT all commits in the repo.
+| Property                                     | Type                              | Description                                                                          |
+| -------------------------------------------- | --------------------------------- | ------------------------------------------------------------------------------------ |
+| commit                                       | `GitCommit`                       | Python object representing the commit                                                |
+| commit.message                               | `GitCommitMessage`                | Python object representing the commit message                                        |
+| commit.message.original                      | `str`                             | Original commit message as returned by git                                           |
+| commit.message.full                          | `str`                             | Full commit message, with comments (lines starting with #) removed.                  |
+| commit.message.title                         | `str`                             | Title/subject of the commit message: the first line                                  |
+| commit.message.body                          | `str[]`                           | List of lines in the body of the commit message (i.e. starting from the second line) |
+| commit.author_name                           | `str`                             | Name of the author, result of `git log --pretty=%aN`                                 |
+| commit.author_email                          | `str`                             | Email of the author, result of `git log --pretty=%aE`                                |
+| commit.date                                  | `datetime.datetime`               | Python `datetime` object representing the time of commit                             |
+| commit.is_merge_commit                       | `bool`                            | Boolean indicating whether the commit is a merge commit or not.                      |
+| commit.is_revert_commit                      | `bool`                            | Boolean indicating whether the commit is a revert commit or not.                     |
+| commit.is_fixup_commit                       | `bool`                            | Boolean indicating whether the commit is a fixup commit or not.                      |
+| commit.is_fixup_amend_commit                 | `bool`                            | Boolean indicating whether the commit is a (fixup) amend commit or not.              |
+| commit.is_squash_commit                      | `bool`                            | Boolean indicating whether the commit is a squash commit or not.                     |
+| commit.parents                               | `str[]`                           | List of parent commit `sha`s (only for merge commits).                               |
+| commit.changed_files                         | `str[]`                           | List of files changed in the commit (relative paths).                                |
+| commit.changed_files_stats                   | `dict[str, GitChangedFilesStats]` | Dictionary mapping the changed files to a `GitChangedFilesStats` objects             |
+| commit.changed_files_stats["path"].filepath  | `pathlib.Path`                    | Relative path (compared to repo root) of the file that was changed.                  |
+| commit.changed_files_stats["path"].additions | `int`                             | Number of additions in the file.                                                     |
+| commit.changed_files_stats["path"].deletions | `int`                             | Number of deletions in the file.                                                     |
+| commit.branches                              | `str[]`                           | List of branch names the commit is part of                                           |
+| commit.context                               | `GitContext`                      | Object pointing to the bigger git context that the commit is part of                 |
+| commit.context.current_branch                | `str`                             | Name of the currently active branch (of local repo)                                  |
+| commit.context.repository_path               | `str`                             | Absolute path pointing to the git repository being linted                            |
+| commit.context.commits                       | `GitCommit[]`                     | List of commits gitlint is acting on, NOT all commits in the repo.                   |
 
 ## Violations
 In order to let gitlint know that there is a violation in the commit being linted, users should have the `validate(...)`
@@ -216,12 +222,12 @@ RuleViolation(rule_id, message, content=None, line_nr=None):
 ```
 With the parameters meaning the following:
 
-Parameter     | Type    |  Description
---------------|---------|--------------------------------
-rule_id       | string  | Rule's unique string id
-message       | string  | Short description of the violation
-content       | string  | (optional) the violating part of commit or line
-line_nr       | int     | (optional) line number in the commit message where the violation occurs. **Automatically set to the correct line number for `LineRule`s if not set explicitly.**
+| Parameter | Type  | Description                                                                                                                                                      |
+| --------- | ----- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| rule_id   | `str` | Rule's unique string id                                                                                                                                          |
+| message   | `str` | Short description of the violation                                                                                                                               |
+| content   | `str` | (optional) the violating part of commit or line                                                                                                                  |
+| line_nr   | `int` | (optional) line number in the commit message where the violation occurs. **Automatically set to the correct line number for `LineRule`s if not set explicitly.** |
 
 A typical `validate(...)` implementation for a `CommitRule` would then be as follows:
 ```python
@@ -281,14 +287,14 @@ As `options_spec` is a list, you can obviously have multiple options per rule. T
 
 Gitlint supports a variety of different option types, all can be imported from `gitlint.options`:
 
-Option Class      | Use for
-------------------|--------------
-`StrOption `      | Strings
-`IntOption`       | Integers. `IntOption` takes an optional `allow_negative` parameter if you want to allow negative integers.
-`BoolOption`      | Booleans. Valid values: `true`, `false`. Case-insensitive.
-`ListOption`      | List of strings. Comma separated.
-`PathOption`      | Directory or file path. Takes an optional `type` parameter for specifying path type (`file`, `dir` (=default) or `both`).
-`RegexOption`     | String representing a [Python-style regex](https://docs.python.org/library/re.html) - compiled and validated before rules are applied.
+| Option Class  | Use for                                                                                                                                |
+| ------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
+| `StrOption `  | Strings                                                                                                                                |
+| `IntOption`   | Integers. `IntOption` takes an optional `allow_negative` parameter if you want to allow negative integers.                             |
+| `BoolOption`  | Booleans. Valid values: `true`, `false`. Case-insensitive.                                                                             |
+| `ListOption`  | List of strings. Comma separated.                                                                                                      |
+| `PathOption`  | Directory or file path. Takes an optional `type` parameter for specifying path type (`file`, `dir` (=default) or `both`).              |
+| `RegexOption` | String representing a [Python-style regex](https://docs.python.org/library/re.html) - compiled and validated before rules are applied. |
 
 !!! note
     Gitlint currently does not support options for all possible types (e.g. float, list of int, etc).