Type checking and schema enforcement

[swo]

          This is shorter as long as we hold to "all actual containers are ndarrays." Which I suppose with #40 we're sort of locking in. Otherwise the paranoia of the original could be useful.

I think what I really want long-term is some sort of schema-like version of Simulation.PROPERTIES which asserts names and the types that simulation will use, so that here we can assert all(isinstance(v, Simulation.PROPERTIES[k]) for k,v in infection.items)

Originally posted by @afmagee42 in #45 (comment)