Enhancement: solutions declare which parameters they can use

[denised]

Currently the only way that parameters are declared is with the AdvancedControls object. The AC object is "flat": it has all parameters that could be used by any solution. This makes it difficult for someone exploring the code to determine what parameters are relevant to any particular solution.

Even if we continue to use AC as a "holder" of parameters, it would be beneficial if there were a way for a solution to declare what subset of AC is used.