grafx - Extensible Java Graphics Package Code

Increasing the qSearchBreadth from 16 to 48. It needs to consider bad moves in
order to decide on effective slide moves.

Preferring the moves that don't have a slide element, all else being equal.

Defining a positionToScore HashMap which will prevent excessive eval()
computations.

Well the sliding has been implemented but I need to optimize.

Splitting dropBlockIntoWell() into two calls, in particular now there is one
which accepts a zStart value.

Replacing the original all-in-one combineWellWithBlock() with two calls, a
slightly modified, non-mutating combineWellWithBlock() and the new
dropBlockIntoWell(). These changes are so that the block sliding after drop is
easier to implement.

Making the experimental level a bit more passable for the computer AI.

Renaming level 23 to level 22, and adding a new level 23 that's very hard.

Changing height of pit on level 23 to 11 (was 10).

Re-calibrating the metrics.
OVERALL_HEIGHT_METRIC: 0.40 -> 0.50
PLUG_THE_HOLE_METRIC: 0.35 -> 0.40
NO_CHILD_LEFT_BEHIND_METRIC: 0.01 -> 0.02