grafx - Extensible Java Graphics Package Code

In NextBlockDisplay, a null block now means still draw the well (without
block).

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.