display: Fix logic for determining whether our focus was successful

In some cases, we can focus the frame window instead of the client
window, so make sure that our checks include that as well.

https://bugzilla.gnome.org/show_bug.cgi?id=715030
display: Use MetaWindow for auto-raise callbacks

This allows us to autoraise Wayland windows... well, except for the
XQueryPointer, but we'll replace that soon.

https://bugzilla.gnome.org/show_bug.cgi?id=715030
window-group: Decompose culling operations into two methods

This also fixes a bug in the translation of clip_region.

We will add an interface for this soon, so we can recursively cull like this...

https://bugzilla.gnome.org/show_bug.cgi?id=714706
window-actor: Move the operations we need to do when we cull out here

Soon, we'll move this into a generic MetaCullable interface, but for
now, just put hardcoded knowledge in MetaWindowGroup.

https://bugzilla.gnome.org/show_bug.cgi?id=714706
cullable: Turn cull_out / reset_culling into a separate interface

Instead of hardcoded knowledge of certain classes in MetaWindowGroup,
create a generic interface that all actors can implement to get parts of
their regions culled out during redraw, without needing any special
knowledge of how to handle a specific actor.

The names now are a bit suspect. MetaBackgroundGroup is a simple
MetaCullable that knows how to cull children, and MetaWindowGroup is the
"toplevel" cullable that computes the initial two regions. A future
cleanup here could be to merge MetaWindowGroup / MetaBackgroundGroup so
that we only have a generic MetaSimpleCullable, and move the "toplevel"
cullability to be a MetaCullableToplevel.

https://bugzilla.gnome.org/show_bug.cgi?id=714706