CycleWS.hs (toggleWS): new function
CycleWS.hs (toggleWS): new function

This is a pointfree adaptation of ViewPrev.viewPrev;
after this patch is applied, it may be a good idea to merge
ViewPrev.hs into CycleWS.hs.

darcs-hash:20071019205323-ae588-674d8f6229ab68d63cf7a324e3278408c569758c

jthornber/XMonadContrib,jthornber/XMonadContrib