TODO

visual mode:
	exec-region = :%!$repl

operators:
	R - multi-char replacement
	undo
	=

motions:
	i/a: iw, i{, ip
	'., '<mark>, etc
	^O, ^I
	*, #

cmds:
	:! / cmd parsing
	:!!
	:e - limit cursor to (x, max_lines) when loading a new file
	:messages - previous ui_status()s
	:g
	:v
	:m[ove] <to-address>
	:c[opy] <to-address>
	:j[oin]
	:d[elete]
	:r[!]
	:a
	:i
	:s
	:<
	:>
	:yank

	:bufdo, :argdo, :args
		:argdo v/Test/s/hi/ge | up

ranges:
	., $, %, +[0-9], '<mark>

use-refactor: command mode is editing a height=1 repl-buffer

registers:
	"[a-z]
	"[A-Z] - append

	@[a-z] - execute register
	@. - execute current line?
	c_CTRL-R_CTRL-W

macros:
	let @a = jjc$yo@a
	macro playback needs to fail on motion fail, e.g. the above
	qa...q records into a
	qA...q records and appends into a
	@@