Basic Cost Learning

Basic automated cost learning. Here are the main features.

The cost learner generates a function called *action*_cost in costlua.asp with learned cost values. It also generates a bunch of easily readably YAML files called costs.1 costs.2 .... in a directory called yaml_costs which can be used to see how costs change as time progresses. We can use this yaml file for plotting graphs of total costs.

I think this PR could be cleaned up a bit more, but I'll tend to that once we restart work on this.

TODO: Figure out which action parameters and original state variables are relevant for learning costs of a particular action.