Parameters trigger visibility of other parameters

[jkiviluo]

When user makes a choice based on a parameter_value_list, it could influence what parameters are enabled for the entity. E.g. choose 'binary_startup' for a unit and you get to use 'startup_cost' parameter (which was disabled before - indicated by being greyed out).

This should work also when the parameter to be filtered is a parameter of another entity_class.

Here are the relevant changes for the DB structure: