Develop class state (against develop)

[rburghol]

NOT READY TO MERGE (Reason: review of concepts pending) -- replaces #202

This PR includes an overhaul to the model state system, leveraging a new object-oriented version of state, which accomplishes the following:

• It streamlines the number of arguments passed to functions, so now, the arg state takes the place of state_ix, dict_ix, ts_ix, ...
• Declarations of the base containers for state attributes is moved outside of the function, living directly in the state.py file, which allows these to be cached, resulting in a huge improvement in performance (recent branches had seen start-up time double due to less optimal numba caching).
• An example of using dynamic equations has been added in tests/testcbp/HSP2results/ to test a 500 equation addon simulation (Use: cp PL3_5250_0001.json.manyeq PL3_5250_0001.json to test).
• Some cleanup of arguments in function like hydr() and sedtrn() to eliminate the argument io_manager as this is no longer used (I think this has been due for a while, I don't think it is due to any changes that I recall making to the code but it seems like a cleaner approach)