* Objects/classobject.c, Include/classobject.h: added __getattr__

and __setattr__ support to override getattr(x, name) and
	setattr(x, name, value) for class instances.  This uses a special
	hack whereby the class is supposed to be static: the __getattr__
	and __setattr__ methods are looked up only once and saved in the
	instance structure for speed