[Xmonad] darcs patch: XPrompt: quickcheck related refactoring (and 3 more)

Hi, I'm in part resending amended patches: I added more useful tests. I also started to document XPrompt a bit. Please forget the previous patches (I'm going to send a message as a reminder). Andrea Fri Aug 17 17:54:54 CEST 2007 Andrea Rossato * XPrompt: quickcheck related refactoring With this patch XPrompt can be tested with quickcheck. As a result getLastWord and skipLastWord has been refactored to avoid possible exceptions. Fri Aug 17 17:56:34 CEST 2007 Andrea Rossato * added a tests directory with quickcheck tests for XPrompt and ShellPrompt Fri Aug 17 17:57:25 CEST 2007 Andrea Rossato * ShellPrompt: quickcheck related refactoring Fri Aug 17 18:28:06 CEST 2007 Andrea Rossato * XPrompt: documentation only