~jaro/balkon

ref: 28ccd0eea7abd52f74e27f388aae4e0979909ca8 balkon/src/Data/Text/ParagraphLayout/Internal/Rich d---------
Fix documentation: link to layoutRich.
Expose piecewise paragraph construction.
Consolidate tree types into one.
Add ancestor boxes to interface.
Implement Rich pagination.
Implement piecewise paragraph construction.
Add basic support for Rich layout.