~jaro/balkon

ref: 8b8b095a2d7cc321b520b3d3dc707f3f0501d2e3 balkon/src/Data/Text/ParagraphLayout/Internal/Rich.hs -rw-r--r-- 3.1 KiB 
Link ResolvedSpan to boxes.

Separate WithSpan for sharing with other modules.

Add basic support for Rich layout.