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.