[KEY FEATURE] Modify model parameters directly in UI

[brynpickering]

A simplification of #10 since it's assumed that the model has already be defined elsewhere and the analyst just has the ability to modify parameter values defined in tables.

Could be considered a duplicate of #26 except that it doesn't require the concept of scenarios to be available in the UI, just the ability to edit data of a model that's been loaded in.

[clizbe]

Yeah I considered this #26 because it's all parameters, but I'll change #26 to keeping track of multiple scenarios.

[clizbe]

Different models/tools require different parameters; 1st order tools should have (virtually) all parameters available through the UI.