grafx - Extensible Java Graphics Package Code

Adding Int32AddPerformance and Int32DividePerformance. Integer divisions are
bad because of the exception handling (ArithmeticException I think).

Optimizing drawLinePosDxDy() just a hair, by pre-computing a slightly different
'xf' and then delaying the decrement to the end of the loop. It's slightly
faster in all cases now. This relies on the fact that [(yy + 1) * dxdy] is
equal to [yy * dxdy + dxdy]. Chopping that "+ dxdy" off essentially.

Adding grafx-2.3-RELNOTES.txt in case I ever lose the README.txt from
Sourceforge file download pages.

Making a release grafx-2.3.

Removing hashCode() from ClipRectangle because I don't like all of these
Java-isms. In fact I'm almost ready to jump ship and try Rust or D.

Removing equals() and hashCode() from FloatColor because it is mutable.

Removing SHORTTERM-TODO.txt because it's done. The integer and 64 bit long
representations of FloatColor don't belong at that level. That would go
somewhere else.

Adding hashCode() to both ClipRectangle and FloatColor. And... [drumroll] ...
I think we're done with 2D for now. Time to focus on correct z computations.

Adding an equals() method to FloatColor.

Updating SHORTTERM-TODO.txt with an item done.