Transition3D: Rendering Issues

[mickleness]

The Transition3D's have a couple of rendering problems:

• The top edge is aliased. I expect it to be smoothed. (The bottom edge is only "correct" (ish) because we're actually calling Graphics2D.clear() with a Shape, so we're giving an illusion of antialiasing half the time.)
• The right and bottom edge of the overall frame are cut off. The left and top edge look OK. It's as if the calculations are off by a fraction of a pixel.

(This is related to issue #26)