~jaro/balkon

ref: efcef179a0e0ca9bf126b3b5a32a8094f55faaf5 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.