grafx - Extensible Java Graphics Package Code

Adding, adjusting comments. This is comments only. But I thought of another
way to do the cast operations, commented on it.

Changing very minor comments, indentations; getting ready for more big changes
though.

Employing the newer strategy with m_foff in 3D graphics line drawing,
interpolated colors. The integer coordinates remain in original space.

Adding some simple comments.

Employing a slightly different strategy in constant color 3D line drawing
algorithm. I discovered this with the 2D code.

Removing some confusing and unnecessary explicit cast, because the cast is
implicit.

Optimizing for the addModAreaPt() call, realized that the integer increment/
decrement can happing in pixel space while the float increment/decrement can
happen in the offset space. This works much better. Need to update 3D
graphics with this same strategy.

This is the first step in getting the line drawing routine in 2D graphics to
use m_foff, which essentially means that it casts to float, as an epsilon
proximity operation, in a space that is far from zero.

Simplifying some arithmetic in line drawing algorithms; when one is subtracted
away from a value, grouping that with the integers before casting to double.

Paving way for m_foff. Early changes.