This makes them much faster, since the display only needs to be updated once.

This can be done efficiently now

Possibly it is showing on mobile safari, despite the zero width parent

Closes #239

Too many hacks were required when not doing this. Also, it can be done cheaply.

Listen to Cmd-X/C instead of Ctrl-X/C on that platform

Well, that was easy.

Closes #237

Closes #238

Much nicer than onKeyEvent

extraKeys option, ability to refer to functions or nonexistent commands, catchall
support in keymaps.