grafx - Extensible Java Graphics Package Code

Pure comment changes. I want to save these comments, because as I'm writing
them I realized that we should do polygon clipping in a pre z normalized state.

Going over more of the 3D rendering code with a fine-toothed comb.

Making some minor revisions to 3D graphics, esp. as related to line drawing.
Mostly just declaring variables as 'final' where it can be done. Optimizing at
least one loop as well.

Adding long comment explaining choice of extents for m_fillPolyClip.

Adding computeIntColor() and friends.

Putting some of the Gouraud shading polygon fill code into nice loops.

Making some very minor improvements to loops and by adding 'final' in some
places.

Streamlining FlatPolyEdgePool & GouraudPolyEdgePool a bit.

Tidying up some little things in FlatPolyEdge & GouraudPolyEdge; for example
marking things 'final' where they can be, and removing all public access.
Improved one 'for' loop in the Gouraud code.

Making some comments in the 3D polygon clippers, and streamlining some code.
This is in preparation for doing a potential overhaul of boundary conditions
when doing clipping.