Clean up and formalize State- and Action-Space typeclasses

[stites]

Currently, there is only a half-baked state space in a poorly-named module. Action spaces are presumed only to be bounded enums (ie: discrete spaces, but we should also account for Box and continuous). This should be moved and functions should be added to so that a user can make state- and action- based informational queries.

[stites]

Hopefully, this abstraction comes out of writing more agents.