Redraw client border when unhiding; during a hide, we just unset
the active flag but never redraw since it'll be in IconicState.

Behaviour reported by sthen@
Stash Class and WM Hints in client_ctx
Remove extra work and simplify client state handling.
Add client wrapper for XWMHints to support XA_WM_HINTS in PropertyNotify
events; based off a diff from Thomas Adam.
apply mwm hints later
since we are drawing in unhide, no need to during client setup
we don't need to manage the save-set since we're not reparenting; left-over from pwin