Generated moves were played twice on the same board. This resulted in moves being sent several times to slaves.

Moves are no longer played twice. Moves should not be possible to play multiple times. New issue will be filed.

Closes #43 @0h30
Error in GTP Command constants led to play command being parsed as version command since this was tested earlier.

Constants updated and an exception added to prevent playing illegal moves. Master (and slaves) will throw an exception on playing illegal moves.

Closes #44 @0h15