Added rotation about an arbitrary center for the image overlay.
Both methods (trig and precenter) included, but trig will be
removed in next commit.
Removed math library - no longer using.  Added crossbar seed.
Added large and small snail seeds.  Menu updates.  Updated pre-
rotate to alpha blend with old background image. Added color cycle
mode tertiary - background. Removed trig drawimage function (it
wasn't pixel-perfect). Added some preload files to the ditribution.
Version update.