Cleanup in X.L.LayoutBuilderP.
Cleanup in X.L.LayoutBuilderP.

Ignore-this: 59d9ce37218424e1bc225a42d71982ab
Remove unused datatype declaration and export usefull typeclass.

darcs-hash:20110514132232-c5067-a40e438b21f60a6c794b8b0ea77c1730b203ce44

jthornber/XMonadContrib,jthornber/XMonadContrib