feat: add config attribute extends

[Shinigami92]

Short description of what this resolves:

We want to support a extendable configuration file
So we introduce a new configuration attribute extends that behave like eslint's extends

Proposed changes:

• Add new attribute extends in configuration

---

Tasks:

• add extension ruleset map
• read new configuration structure
• pass config through to verify
• add tests
• define recommended ruleset

[Shinigami92]

@thedaviddias Ready for review! 🎉

At first, you can only focus on changes to the source files
Then, if you want, also look at the test files

We are getting closer to the release of version 1.0.0 😃

[Schweinepriester]

This was automatically closed without conclusion; extendable configuration is still desirable imho.

[codecov]

Codecov Report

Merging #489 (59d55ca) into beta (e459672) will not change coverage.
The diff coverage is n/a.

❗ Current head 59d55ca differs from pull request most recent head a763b2e. Consider uploading reports for the commit a763b2e to get more accurate results

@@     Coverage Diff     @@
##   beta   #489   +/-   ##
===========================
===========================

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e459672...a763b2e. Read the comment docs.

[gitrequests]

Configuration merge is still not available?

[ghaschel]

No news on this? This is a must-have feature in every linter imho.

[donroyco]

Any update on this PR? It would be really helpful when this functionality lands in HTMLHint.

[Kristinita]

Are there any chances that this feature will be implemented to HTMLHint?

Thanks.

[coliff]

thanks for all your contributions @Shinigami92
:-)

This PR was made 5 years ago and going to the Beta branch which we no longer use, and the codebase has changed a lot since then so I think it makes sense to close this for now... We want to change all the recommended rules, but that can't/won't be done until a major new version (v2) and there's lots to be done before that...