grafx - Extensible Java Graphics Package Code

Well apparently that code needed a slight '++' correction.

First attempt at adding flat shading version of fillPolygon() which is
optimized just for that. This may not even compile; definitely not tested, but
in theory it may just all work.

Unwinding some loops to improve performance of Gouraud fillPolygon(), renaming
some variables for clarity.

Paving the way for improved performance flat shading.

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.