Started AI interface

The script now takes parameters for how you want to run it:
  Game Type: 'a' for AI and 'h' for human
  Num players: 2-4
  Difficulty: 0-3

Created seperate play_game_human and play_game_ai methods. play_game_ai will require more work. it is currently the same as play_game_human except it makes AI_Agents instead of Human_Agents

Made AI_Agent inherit from Human_Agent. So it will work for now but most methods will have to be overwritten so they can be modifed slightly