[Xmonad] darcs patch: add sketch of tabbed layout. (and 3 more)

I now display window names in the tabs (which are still hideous). Still needs work to get expose events. David Sun Jun 10 08:39:26 PDT 2007 David Roundy * add sketch of tabbed layout. Sun Jun 10 08:39:39 PDT 2007 David Roundy * add Decoration module to be used to easily define decorations. Sun Jun 10 09:36:51 PDT 2007 David Roundy * make Decoration draw the window initially. We still don't respond to expose events. :( Sun Jun 10 09:37:29 PDT 2007 David Roundy * display names of windows on tabs.