~jaro/balkon

ref: 8537ba994a9fe1d81fd7138dfceef32f718b8231 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.