Since the surface actor knows more about how it draws itself, instead of
pushing texture state (buffer and scale), input region and opaque region
from MetaWaylandSurface after having transformed into what the surface
actor expects, make the surface actor set its own state given what state
the Wayland surface is in.
https://bugzilla.gnome.org/show_bug.cgi?id=744933
The current shadow code just uses a single fixed texture (the Gaussian
blur of a rectangle with a fixed blur radius) for drawing all window
shadows. This patch adds the ability
* Implement efficient blurring of arbitrary regions by approximating
a Gaussian blur with multiple box blurs.
* Detect when multiple windows can use the same shadow texture by
converting their shape into a size-invariant MetaWindowShape.
* Add properties shadow-radius, shadow-x-offset, shadow-y-offset,
shadow-opacity to allow the shadow for a window to be configured.
* Add meta_window_actor_paint() and draw the shadow directly
from there rather than using a child actor.
* Remove TidyTextureFrame, which is no longer used
https://bugzilla.gnome.org/show_bug.cgi?id=592382
