Implement MS TextWorld environments

[doctorcorral]

Microsoft has released TextWorld, a tool for creating text-based environments for training conversational gents.

Environments can be created with tw-make giving .ulx files.

A TextWorld environment must be registered as a gym environment like this:

env_id = textworld.gym.register_game("game_path/game.ulx",
                                     max_episode_steps=50)

env = gym.make(env_id) 

Take Gyx.Gym.Environment as a reference