Unit tests & bug fixes for counter-renderers.

Merge branch 'main' of git.adrian.geek.nz:/srv/git/haskell-stylist into main

Fix breaking dependency.

New releases of all hackages! + code tidies.

Parse @layer rules.

Tweak priority to be a list for the sake of cascadeLayers.

Remove Stylist-Traits APIs from Stylist Core, leaving backwards-compatible stubs.

Fix build failure against new enough versions of 'text'.

Expand permitted base versions.

Expand permitted base versions.

Expand supported base versions.

Release version 2.4!

Add support for `@document regexp()`..

Release Haskell Stylist 2.2!

Release new Haskell Stylist & XML Conduit Stylist!

XML Conduit Stylist changed to abstract away Haskell Stylist's breaking datastructure changes.

Rewrite trivial cases of :where & :is.

This is mostly for the psuedoselector rewrites performed in Data.CSS.Preprocessor.PsuedoClasses

Implement psuedoclass rewrite rules.

Implement CSS3 counters.

Parse CSS counters.

Provide utilities for rewriting CSS-referenced URLs.