Added parser & internal logic for TurnOrder object, but not yet using it
Moved all definition-reading code into Game.parse function, made it now check node names and fail gracefully
Turn order is now parsed into the game object, but not used
Now using TurnOrder type, which has added the ability to step backwards (in effect, it's a form of doubly-linked list now).

Also refactored AlphaBeta AI, removing its propensity to aim for stalemate.