geom.Path: Simplify de Casteljau algorithm.
geom.Path: Simplify de Casteljau algorithm.

Because we only need to consider cubic Bezier curves, we don't need to
use recursion and we simply need to subdivide three times to get a point
on the curve.

When running the tests in Neko, this cuts down the runtime in half:

./test.hxml  6.74s user 0.03s system 100% cpu 6.768 total
./test.hxml  13.12s user 0.05s system 100% cpu 13.161 total

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@redmoonstudios.org>

aszlig/hase