grafx - Extensible Java Graphics Package Code

Carrying over all the changes from my sandbox ('blockout' project) as related
to grafx and grafx_3d. This is beginning to look really outstanding! There
are some small changes I need to look into before the next release.

Allowing a more fine-grained choice of ZBITS, namely any integer between 8 and
24, including those two boundary values.

Making use of import java.math.BigDecimal.

Adding test code: AliasWeirdness.

No longer requiring that zFront >= zBack.

Adding one more thing under MAJOR TODO.

Donut restored. Getting about 1ms frame renders.

Adding ZBITS_28.

Initial pass at trying to compute quick 'n' dirty z values.

Cutting out the commented out experimental setPix() code. That experimental
code has been put into Donut, when it uses PIXBUFF_ABSTRACTION.