Each window is now reparented under a window created by awesome. This window is
NOT visible, this commit should not cause any visible differences. Instead, this
is done to work around problems with X11.
The only alternative would be to ban windows by moving them offscreen which is
ugly in itself and breaks pagers. Doing it like this seems to be the better
solution.
Signed-off-by: Uli Schlachter <psychon@znc.in>