grafx - Extensible Java Graphics Package Code

Fixing a couple of Javadoc generation warnings.

Updating version numbers in build scripts:
grafx: 2.0 --> 2.1
grafx_3d: 1.0 --> 1.1
These are more than just bug fixes. There are major performance improvements
and minor API additions.

Moving the latest 3D rendering graphics library changes into 'grafx' branch.
Getting readier and readier for release.

Allowing ZBITS to reach zero.

Carrying over the delicate changes to z space strategy to 'grafx' branch, after
thoroughly proofreading the diffs.

Adding missing class RasterDepthPixBuff.

Working on moving around TODO comments.

Removing a TODO that's already finished.

Fixing spelling error in comment.

Comment and Javadoc improvements.