~jaro/balkon

ref: aec7239639788d9ab4ad9cbbeb71e82f3defbee4 balkon/test d---------
Implement line breaking on code point boundaries.
Implement run splitting.
Store span index in ResolvedSpan.
Link to Span using a generic wrapper.
Implement absolute line heights with half-leadings.
Use CSS-compatible line height settings.
Fix pretty printing for fragmented spans.
Upgrade Fragment to contain pen position.
Clean up ParagraphConstruction.
Use infix operators for constructing test data.
Implement "plain" interface.
Create "plain" interface.
Add module for working with rectangle coordinates.
Add explicit scale to test font.
Automatically discover test specs.
Separate tests by module.
Add unit tests for spanToRuns.
WIP version with WIP interface.