changes client Game to only try moving if game is still in progress
adds _isInProgress and _gameOver to client Game
adds getPlayerName to client Game
adds empty Clock module to client - it will handle keeping time on the client
and synchronising it with the server
adds null check to server Game _move - necessary now that chess Game has been corrected not
to allow moves when not in progress
adds server time/latency estimation functionality to Clock
adds client Clock and getTimeLeft method to client Game
adds getTimingStyle method to client Game