Multiple inheritance

Multiple inheritance, bound/unbound methods, classmethod, staticmethod and super() enable cooperative multiple inheritance is passing all python reference tests, all multiple_inheritance tests except one, and fixes several reported bugs, more details in:  https://github.com/brownplt/lambda-py/commit/fa69d52067f32797720a22da37da4b25d8616be2
NB: the failing test is related to inheritance from builtin classes, this need to be discussed, including the implementation of the __new__ constructor, perhaps after integration with of the new scope.