[cairo] Fun With Pixman

[Lawrence D'Oliveiro]

Convolutions are such neat things
<http://default-cube.deviantart.com/art/Faux-3D-Ball-576929145>, if a
bit slow. Though I found a use for a simple Cairo linear gradient as
well.

Source code here
<https://github.com/ldo/python_pixman_examples/blob/master/faux_3d_ball>.