#5 Gradient support for PyGame Renderer

[Evan Jones]

This patch applies against the CVS tree. It adds support for
gradients to the 2D renderer. This makes the default theme look
MUCH better. However, as the gradients are calculated in Python
code, there are some performance problems. The gradients are
agressively cached to reduce the time required when resizing
windows, but there are still pretty serious delays.

[Evan Jones]

PyUI Gradients for the PyGame Renderer