Requires a few fixes to properly work in the stage3d openfl target.

Somewhat optimized, still rough prototype. No line support, no gradient support.

AA must currently be done through MSAA. Inner edge AA, still not implemented.

Sources:

http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html

http://staffwww.itn.liu.se/~andyn/courses/tncg08/sketches06/sketches/0125-kokojima.pdf