[Xmonad] HEADS UP xmonad-library merge

[Spencer Janssen]

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