Merge in Nathan's code updates, and document what these changes consist of

[micahcarroll]

Todo:

• Check whether this branch works correctly even with the master branches of human_aware_rl and overcooked_ai

[micahcarroll]

Me and @jyan1999 decided to not merge this because at this point we have achieved reproducibility and we're not necessarily interested in the new layouts. This can be responsibility of whoever wants to use them in their research