Randomize parameters of a module

[danngreen]

This could be a button on the ModuleView page (consider similar placement to "Auto-patch" button #269).
It would randomize all parameters of the module.

VCV-rack ported modules have a randomizeEnabled flag for each param, it would be great to respect that. CoreModules do not have anything equivalent so we could add an onRandomize function to the CoreProcessor base class, and let CoreModules override it. --> moved to Issue #290