Pushes applying clip rectangles up into GraphicsObjectData.

65faeb2a9b4eb4970429592ec72b113a9328db46 was the first time we attempted
this. It was reverted in c384255964a1db118f0b294e5ee39e0735757f1c because
it broke rendering of Yumemi's face in Planetarian during her final scene.

(I suspect that this only accidentally used to work.)
Implement "own" clip rectangles.

RealLive has a second system of clip rectangles that are relative to the
object's origin instead of relative to the screen. Implementing these makes the
Little Busters battle system scroll text properly.
Cut the image cache size in half.

In Little Busters, this shrinks the cache hit rate from 69% to 66%. In
Planetarian, 10 images in cache has a hit rate of 75%.
Prune dead Kanon AVG32 code out of xclannad.