Rhino rendering UI wish - better separation of plugin materials based on active renderer

@andy It doesn’t even have to be a fundamental paradigm change from your end. You can still keep the idea of the “abstract” Rhino intermediary material … but a lot can be done with a more empathic content aware UI.

For example, when creating a new material, Rhino should sense the current renderer is Bella and collapse the Rhino Basics to avoid the visual clutter.