Metaclass inheritance and attribute/associations raising #423

Autogenerated Python classes should follow meta-model inheritance hierarchy. Raising properties and associations should also be done in such a way that the property and association is raised through the inheritance hierarchy to the abstract meta-class whose all inherited meta-classes contains those attributes and associations.

This would allow for more use cases where a proper Python hierarchy is needed (e.g. examined at runtime, or alignment with existing meta-models)