grafx - Extensible Java Graphics Package Code

Removing the m_modRect calculations from RasterDepthGraphics. Such a feature
does not really go well with 3D graphics.

Changing the sensitivity of user interface in Donut.

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.