hyper-optimized alpha-zero implementation with ray + cython for speed

train an agent that beats random actions and pure MCTS in 2 minutes

• train.py: distributed training with ray
• ctree/: mcts nodes in cython (node.py = pure python)
• mcts.py: mcts playouts
• network.py: neural net stuff
• board.py: gomoku board

• ray distributed parts (train.py):
  • one distributed replay buffer
  • N actors with the 'best model' weights which self-play games and store data in replay buffer
  • M 'candidate models' which pull from the replay buffer and train
    • each iteration they play against the 'best model' and if they win the 'best model' weights is updated
    • include write/evaluation locks on 'best weights'
  • 1 best model weights store (PS / parameter server)
    • stores the best weights which are retrived by self-play and updated when candidates win

• cython impl
  • ctree/: c++/cython mcts
  • node.py: pure python mcts

-- todos --

• jax network impl
• tpu + gpu support
• saved model weights

• based off: https://github.com/junxiaosong/AlphaZero_Gomoku
• distributed rl: http://rail.eecs.berkeley.edu/deeprlcourse-fa18/static/slides/lec-21.pdf