grafx - Extensible Java Graphics Package Code

Starting to move stuff around in GenerateBlocks.

And, this is possibly the last Javadoc change in BlockGenerator. I need to
move on to the code in GenerateBlocks because there are some problems.

Filling in some missing Javadoc.

Getting rid of IllegalStateException usage in BlockGenerator. Making things
consistent.

Fixing some Javadoc issues and marking an unused function as 'private' in
BlockGenerator. Just wrapping up with this class. Nearing completion.

Making a few minor optimizations and documentation changes.

Making an optimization to equalsModuloOrientation().

Marking two more functions that are not being used externally as 'private', in
BlockGenerator.

Tidying up some functions that aren't being used anywhere.

Modifying comment above putUniqueOrientedBlock().