Because a PropertyMaterialList property is used now it makes no sense any more to pass a list of view providers to the dialog
as it's impossible to set the material at a certain index.
Therefore the dialog has been simplified and setting the material property must be done by the calling instance.
Improves the use of the ShapeAppearance property for the Part workbench.
removes DiffuseColor property
adds Python compatibility using custom attributes
transitions DiffuseColor to ShapeAppearance on open
Improved UI elements for setting object appearance, and appearance per face
Lays the foundation for future texture support
* On lines where the variable type is obvious from inspection, avoid repeating the type using auto.
* When possible use a ranged for loop instead of begin() and end() iterators
