~jaro/balkon

ref: 0e108aa71ac0cce0b8d819a0528dba4be37c9bf6 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.