Commit extracted property-parsing code from Graphics.Layout.CSS

Refactor tree to aid future dev (Inline layout got a major overhaul anyways...)

Fix fontsize handling.

Correctly reporting surrounding whitespace on inline elements.

Incorporate CSS Box Model into positioning inline ancestors.

Correctly assign positions, prepare to incorporate padding into size calc

Compute boxes & positions.

Reconstruct inline tree.

Refactor to use newer Balkón APIs.

Add support for logical properties thanks to Stylist Traits update.

Implement property prioritization & shorthands.

Build utility for parsing CSS3 Grid templates.

Add missing field into testsuite.

Reference document main module.

Describe remaining submodules.

Add descriptions of CSS property-parsing submodules.

Reference-document generic layout/tree-traversal, seperate natural from final size fields.

Reference-document inline layout.

Reference-document grid layout.

Reference document flow layout module.

Decided against adding invisible length-lowering into CatTrap, Mondrian's would be too sophisticated!