~jaro/balkon

ref: 4ebfe390a1e8b16f42c6bdb51c135c895a7ce022 balkon/src/Data/Text/ParagraphLayout/Internal/ParagraphExtents.hs -rw-r--r-- 925 bytes 
Allow paragraphRect without point 0,0.

Parametrise rectangle union bias.

Separate interface-independent constants.