mem_el_borrowed -> mem_el.
run functions now pass Mem args.
it_mem macro.
host functions now take Mem args.
reinstated -Wunused-functions for release build.
replace Hash_bucket struct with Array type alias.
comment.
changed order of prepend args; better error messages.
comment.
silence string literal length warning.
refactor.
fixed use of FMT_STR, str_find_line_start off-by-one.
factored out str_append.
expand.h (empty).
relax mem assertion.
comment.
better function call error checking.
preprocess.
prepend, append work.
fix str_append bug.