~jaro/balkon

ref: dfa301d6c0659e437ae66d72787a23b4393b33f2 balkon/test/Data/Text/ParagraphLayout/PlainSpec.hs
Move non-public modules into Internal namespace.
Add test for RTL text.
Remove obsolete TODO.
Test line splitting with many runs.
Implement line breaking on code point boundaries.
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.
Implement "plain" interface.
Create "plain" interface.