SimulateOde leaves DeterministicOde redundant

[j-c-gibson]

As the new documentation outlines, we only need to use the SimulateOde class to access all the features of PyGOM. SimulateOde inherits from DeterministicOde which itself inherits from BaseOdemodel. It might make sense to cut out this intermediate step and also to split the class definition over multiple files since they are currently very long.