Return handling is done in ui, not :p
Use line length and per-line in list_iter_region() - fixes :g/re/p

g_exec() now only makes one hit per line

Cherry-pick from c55f7c0d7cd49e91848c7bd93d7b1de2eb531077

Conflicts:
	buffer.c
	complete.c
	complete.h
	keys.c
	list.c
	list.h
Added note about :g//'s sub-range parsing