~jaro/balkon

ref: 35a5cc75e3831fa3139ebb43dcf2e0948a76be16 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.