While a window is in the save set, it will automatically be made visible again
when awesome exits/dies. This makes sure that the next window manager will pick
this window up and handle it properly again.
But when a window explicitly asks not to be visible, it doesn't want to be
visible. Even if awesome dies. So we should remove the client's window from the
save set in client_unmanage.
Thanks to anrxc and his xwrits.
Signed-off-by: Uli Schlachter <psychon@znc.in>
e773eecc03