Added support for multiple inheritance when inheriting from one base class and/or multiple interfaces.

Added a unit test verifying that it works with a simple class and interface. This unit test would previously have failed since multiple types are in the class super class list.

- Added exceptions during unintended use of superclasses.
- Removed invalid comment.
- Improved exceptions from MetaType slightly.

* 1783 Implement Interface And Inherit Class

Added support for multiple inheritance when inheriting from one base class and/or multiple interfaces.

Added a unit test verifying that it works with a simple class and interface. This unit test would previously have failed since multiple types are in the class super class list.