Two new floating window ManageHooks.
Two new floating window ManageHooks.

Adds doRectFloat, which floats the new window in the given rectangle; and doCenterFloat, which floats the
new window with its original size, but centered.

darcs-hash:20080225183337-d53a8-e9e6680266618483dec2cd900e9be8219e1e89f7

jthornber/XMonadContrib,jthornber/XMonadContrib