grafx - Extensible Java Graphics Package Code

Making getPointAlias() a static function, because it's algorithm-related, and
not state-related.

Making a preliminary implementation of VectorUtils.sliverContainsSamplePoint().
Had to make some necessary changes to VectorUtils, to the new functions there.

Dropping the EPSILON back face culling from drawPoint(). Adding function
dotProductXY() to VectorUtils.

Fixing a spelling error in Javadoc and adding a signature to
sliverContainsSamplePoint() in Donut.

Adding a stub for sliverContainsSamplePoint() in Donut. There is a large
comment explaining this, but the signature/implementation have not been done
yet.

Adding a comment explaining the barebones method of computing facet normal,
with a reference to Newell's algorithm.

Moving the new functions into VectorUtils where they belong.

In Donut, adding crossProductXY() and vectorXY().

Struggling with the Donut code to draw vertices.

Removing two unnecessary blank lines.