~jaro/balkon

ref: 4415c30c05dab911c592dfcbcfed8d3b46b8d87c 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.