X.A.DynamicWorkspaces: fix addWorkspace and friends so they never add another copy of an existing workspace
X.A.DynamicWorkspaces: fix addWorkspace and friends so they never add another copy of an existing workspace

Ignore-this: 5bfe8129707b038ed04383b7566b2323

darcs-hash:20091112201351-1e371-ed6aeb650d2e9d6a4c131e8f7a36b922b8f1d905

jthornber/XMonadContrib,jthornber/XMonadContrib