[xmonad] darcs patch: X.A.Navigation2D

Finally, Wirt and I think this is ready to be shared with the broader xmonad community. Wirt certainly deserves credit for lots of useful feedback and lots of thorough testing I wouldn't have had the patience to do. 1 patch for repository http://code.haskell.org/XMonadContrib: Thu Dec 8 16:58:42 AST 2011 Norbert Zeh <nzeh@cs.dal.ca> * X.A.Navigation2D This is a new module to support directional navigation across multiple screens. As such it is related to X.A.WindowNavigation and X.L.WindowNavigation, but it is more general. For a detailed discussion of the differences, see http://www.cs.dal.ca/~nzeh/xmonad/Navigation2D.pdf.