[Xmonad] HEADS UP xmonad-library merge

Firstly, because of all these changes, we recommend backing up your Config.hs before pulling these patches. We've just merged the xmonad-library branch, which brings some major changes. User configuration now goes in ~/.xmonad/Main.hs. The installed xmonad executable builds and runs this configuration file at runtime. XMonadContrib is now built and installed as a separate step, simply do the usual Cabal installation procedure after installing the xmonad library. This is a big transition, bear with us as we smooth out the rough spots. Cheers, Spencer Janssen