grafx - Extensible Java Graphics Package Code

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

Increasing millisBlkMvTime from 180 to 200.

Adding levels 18, 19, 20, & 21.

Removing all println() statements for now.

Adding capability to slide a block after it hits bottom.

Lessening NO_CHILD_LEFT_BEHIND_METRIC.

There was an error in the "no child left behind" metric - wasn't being scaled
by ten.