Added a random AI (ie. an AI that will blindly choose a legal choice given any gamestate).  Getting memory overflows now because AIControllerImpl does its 500 ply iterations regardless of whether there's been change.  I think, at least.
Fixed memory overflow - ply increases were kept for children instead of decaying, leading to exponentially-increasing GameStates.  Now it's much faster + reliable.

Tested against random AI, and beats it 55% of the time... so, yeh.  Kinda works.