Added a unit test which consists ofa python class inheriting from a C# class which has a virtual generic method. In this version, this causes a InvalidProgramException to be thrown during class creation.

Previously an exception was thrown during class creation if the python class inherited from a class with a virtual generic method.

This has been fixed by ignoring generic methods when creating overloads in the generated class. Note, this means that generic virtual methods cannot be overridden in python code.

- Changed the behavior so that a .NET is always created when the base type is also a .NET type.

- Added shortened Attribute aliases which just generates tuples.
- More general CLR base class support - creating a class instance from C# is now more similar to creating one from python.
- Added attribute decorator to clr.py.
- Added testing for the various possibilities

- Fixed search bug in AssocAttribute
- Added testing

There are small typos in:
- pythonnet/__init__.py
- tests/test_import.py

Fixes:
- Should read `splitted` rather than `splited`.
- Should read `loaded` rather than `laoded`.

Signed-off-by: Tim Gates <tim.gates@iress.com>

Added support for specifying attributes on property-methods (eg. get/set attributes).