grafx - Extensible Java Graphics Package Code

Adding line of commented out code. The old call to coveredHoleMetric().

Making some fairly simple, straightforward optimizations to the code. Just
trying to squeeze out a tiny bit of better performance; this will hardly make a
difference actually.

Changing level twenty three from 6x5 pit to 7x5. A tad easier.

Adding stuff to TODO.txt.

Making level 23 much harder by reducing the pit size. Now it has no problem
passing this, with the improved covered hole metric. 7x6 -> 6x5.

Changing qSearchBreadth from 32 to 16. I think I may need to optimize the new
CoveredHoleMetric a little bit.

Now going to test new CoveredHoleMetric function.

Finished CoveredHoleMetric. Now to plug it in.

Fixing another small bug in computation of total, forgot to cast int to double.
In CoveredHoleMetric.

Fixing one little issue by negating canPlugHoleWithoutPlacingCubeAbove().