grafx - Extensible Java Graphics Package Code

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.

Moving the zFront/zBack definitions into RasterDepthPixBuff.

Filling out the Javadoc in RasterDepthPixBuff.