Added GridVariants.SplitGrid
Added GridVariants.SplitGrid

GridVariants.TallGrid behaved weird when transformed using Mirror
or Reflect.  The new layout SplitGrid does away with the need for
such transformations by taking a parameter to specify horizontal
or vertical splits.

darcs-hash:20090129152146-18a2b-a1b4d6b5d4810cc496f268259356edf2ed79000b

jthornber/XMonadContrib,jthornber/XMonadContrib