grafx - Extensible Java Graphics Package Code

Adding TODO comment above getCenterOfMass(), which further explains the problem
that we are dealing with.

Adding long comment to the top of findBestBlock(), which is private. The
purpose of this commit is to advertise my intention. I will be needing help.

Putting BlockMirrorImageCheck to a somewhat finalized state. We have a lot of
work to do. The idea of "canonical" totally disregarded reflections. We need
to fix that.

Uh oh. We have a problem, Houston. BlockMirrorImageCheck has discovered an
anomaly.

In BlockGenerator, adding getMirrorBlockZ(). Untested.

In BlockGenerator, adding equalsModuloOrientation(). Untested.

Using what seems to be the correct curve for UniformScale3D, during inversion.

Fixing the sqrt() of negative number issue. D'oh! Lol. All of this is so
related.

Backing out the NaN handling in line clipping as promised in previous commit.

Quickie fix for NaN handling in line clipping strategy. This fix isn't
satisfactory without more comprehensive tests for points, lines, and polygons.
Committing this and will then immediately back out, I may resume on proper NaN
handling at some later point in time.