- Added functions in core.clj to be used in MCTS:
  - terminal? (boolean if the game is over)
  - get-scores (returns map of scores per player)
  - playout (randomly plays game to completion & reports results)
- Added doc comments in many functions in core.clj
- Fixed a bug in ttt_relations_mapwhere I wasn't using the environment
  correctly when I tried to use the :open relation in terminalo.