grafx - Extensible Java Graphics Package Code

In 3D graphics with the new floating point casting strategy, starting to
implement some of the polygon filling stuff.

Carrying over the xf/yf changes in line drawing for the color interpolated code
too, this is so that the cast to float happens right around 1.0.

In 3D line drawing of constant color, starting to implement the correct xf/yf
strategy where it's being compared against 1.0f.

Correcting a comparison to 0, i.e. 0.0d.

Touching upon the color interpolated line drawing routines in 3D graphics, now
using pixel() call in some places to chop off accumulation errors.

Incorporating more usages of the new pixel() function.

Starting to implement the better casting strategy to chop accumulation errors.
This strategy was originally developed in the 2D rendering code. Moving the
changes into 3D rendering one small step at a time, and testing along the way.

In FloatPolyEdgePool, where access was 'public', making it only package
visible.

Clearing up some Javadoc issues in RasterFloatGraphics; getting rid of member
variable m_nullEdges.

Fixing some remaining Javadoc issues in com.nerius.grafx.d2.FloatGraphics.