grafx - Extensible Java Graphics Package Code

Adding class FlatPolyClipper.

Improving performance by just a tad by not accessing arrays when the values are
stored in existing variables.

Improving performance by just a tad, by unwinding loops.

Adding classes FlatPolyEdge and FlatPolyEdgePool, not being used yet.

Adding a private constructor to FloatPolyClipper.

Renaming DepthPolyClipper to GouraudPolyClipper, DepthPolyEdge to
GouraudPolyEdge, and DepthPolyEdgePool to GouraudPolyEdgePool. I want to make
a parallel set of objects that do flat shading; I decided that having the same
edge class do both would be a bit confusing in the code.

Adding a comma in a comment.

Adding some cool options to Donut: CLIPPING_DEMO & COARSE_MESH.

Streamlining instantiations of DepthPolyEdge.

Adding class DepthPolyEdgePool. This is to recycle edges.