~jaro/balkon

ref: 024cddaac622db5ccd0d57c48ba1b06a1eaf82a8 balkon/test/Data/Text d---------
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.
Separate tests by module.