grafx - Extensible Java Graphics Package Code

nextBlockChanged() set to null if no more NewBlockStartsEvent in stream. This
is better than displaying a lingering block, which is the last block in play.
Better to display nothing in that case.

Making progress on the nightmare mode playback.

Moving the recorder logic from NightmareModeAction into NightmareLevelTest.

Adjusting scoreMultiplier details.

Carrying over the additional scoreMultiplier field to NightmareModeLevel.

Adding scoreMultiplier field to Level.

Adding a block of code to NightmareModeAction that will record a game to file.
This code block should be moved to a higher level because we need to insert
something in the info string, namely the score multiplier.

Nearing completion on LaunchNightmareLevelPlayback.

Adding beginnings of LaunchNightmareLevelPlayback. Not done yet.

Fixing the FloatPolyClipper with a boundary condition which would lead to
NullPointerException. It seems like a harmless change but it has a huge
impact in very specific cases. This change had already been made to blockout
project, and is tested. Just rolling the fix into this repo. Some benign
comment changes, and benign debug method additions as well.