[Xmonad] darcs patch: eliminate a few Eq a constraints in Stac... (and 1 more)

A couple of little cleanups, preparatory to moving Layout into StackSet (which is preparatory to using the Read/Show instances of Layout). David Thu Sep 20 17:01:43 EDT 2007 David Roundy * eliminate a few Eq a constraints in StackSet. Thu Sep 20 17:05:27 EDT 2007 David Roundy * remove unneeded Ord constraint.