Need to look into box2d engine to set env params. Also make module-global parameters local to class so different environments can have different parameters

Implemented 2nd order, 1st order, reptile approximations to meta-update;
Possible bugfix in tanks system;
Implemented Standard MAML for comparison;
Switched to Jensen-Shannon distance for pruning library of policies;
Added ranking function for selecting policies;
Added seeding for reproducibility (some left);

Bugfix with cache to episode conversion in utils.py. Done flags can either omit terminal state or initial state of next episode.