dmenu exits with code 1 when you hit Escape, and I wanna create a contrib that
takes advantage of that.
This required changes in four contribs (Commands, DirectoryPrompt, ShellPrompt,
and WorkspaceDir), and might require changes in users' Configs. Also, I'm not
sure some of the changes I made to the client code are very Haskelly. Would
appreciate input there.
Actually, it sets the current directory in a layout, since there's no way I
know of to attach a behavior to a workspace. This means that any terminals
(or other programs) pulled up in that workspace (with that layout) will
execute in that working directory. Sort of handy, I think.
