let clients track their urgency, per ICCCM
let clients track their urgency, per ICCCM

This removes the dependency on redoLayout -- now WithUrgencyHook defines handleMess only.

darcs-hash:20071111021241-78224-fa4fa870f64f24bb4ea227242fc5775dd68a151a

jthornber/XMonadContrib,jthornber/XMonadContrib