getShellCompl is useful for writing prompts in Config.hs or even full standalone prompts; and personally, if a small utility function like 'split' can be exported, how much more so something useful like getShellCompl?
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.
