If not using sticky mode (the default), clients aren't automagically
assigned a group, thus cc->group will be NULL - fix the client group
shortcut in menu lists; crash reported by Christian Neukirchen.
cvsimport
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
cvsimport
ICCCM explicitly states that server time (CurrentTime) should *not* be
used for focus events, but rather the timestamp of the generated event.
Track the last event timestamp and send it down for a WM_TAKE_FOCUS
ClientMessage.  I suspect we should do this for clients that don't
announce this Atom as well, though the raciness gets us into a bind.

Solves focus order issue since WM_TAKE_FOCUS; fix verified by sthen@

ok sthen@
Make sure we really take work area gap into account with snap calculations;
from Dominik Honnef via Christian Neukirchen.
cvsimport