created new class entities.Ai
hooked up the only AI I've currently got in the game, BasicMonster and ConfusedMonster.
had to edit the monster generation in maplevel.place_objects() to create the Ai class and set the ai to BasicMonster()
also had to edit BasicMonster to set the monster = self.owner.owner, since we are one more level down.

Improvements needed:  separate AI functionality into modules and set up parameters to control/fine-tune them.