Generic ParameterizedFunction

This adds the ParameterizedFunction(f,params) which wraps a generic user function for the parameter estimation routines and does not require definition via the macros. While this could be done before by hand, this is a nice convenience which will help less advanced users.

DiffEqBase Max Version

This puts a maximum version on DiffEqBase because it will be changing

abstract ParameterizedFunction

to

abstract AbstractParameterizedFunction

so that way ParameterizedFunction can be a concrete type with a constructor from this package which makes an AbstractParameterizedFunction from a user-defined function.