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

Fix @layer to play nicely with the conditional at-rules.

If you're not using that, its still integrated into core.
Since the @layer rules are stripped by ConditionalStyles this shouldn't make a difference.

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

Improve documentation, release version 1.2

Write reference documentation.

Request @import'd styles concurrently.

Let user & useragent styles query for a lack of author styles.

Introduce simplified html2css API

Which, now that these are implemented, lowers <style> to @media & <link rel=stylesheet> to @import.

Unittest conditional styles, add loadImports API to fit Rhapsode's use.

Test rules capturing of ConditionalStyleSheet.

Fix: ConditionalStyles reversed CSS precedance.

Fix precedence of conditional blocks (+API redesign)

Implement @supports.

Draft interpretor for @supports.

Implement @import & @media

Dependency injection required for an HTTP client library.

Fix syntax errors in ConditionalStyles

Support multiple @document conditions (FIX)

Switch @document from conjunctive conditions to disjunctive conditions.

Implement @document rules (save regexp() conditions).

I've still got to select a regexp library to power it.