Bezier curve support

[de...@gmail.com]

I added support for stroking 3d quadratic and cubic bezier splines.
The way it works is very simple---project all points and control
points into 2d, and use the <canvas> support for drawing 2d splines.

I posted a very simple example of this new code, a spiral:

http://deanm.github.com/pre3d/

I was thinking about how this could be extended for fills and shapes
based around beziers, but it seems like it could get hairy. I
encourage you to experiment with the new code, and let me know if you
have any ideas.

Thanks,
Dean