Define zip-with
Define sum
Define replicate
Define list <-> index-hash
Add string.rkt
Use make-immutable-string
Use replicate
Define styled-block-size
Define styled-block-expand
Improve styled-fill-line
Define styled-block-append-[horizontal/vertical]
Add markout.rkt (WIP)
Calculate document densities
WIP
fixes
fixed tests
col width allocation
block extension/append
chains
fixes