Work around Zope Interface package's new-style class/metaclass bug

Use this as a metaclass of any new-style class you'd like to have properly support __implements__ and __class_implements__, as current versions of the Zope Interface package can't tell that a metaclass instance is really a class-like thing.

Basically, this does two tricks. First, it converts any __implements__ value in the class dictionary to an interfaceAssertion attribute descriptor. Second, it provides instancesImplements and instancesImplement methods to its instances, so that when looking for isImplementedByInstancesOf, the Interface package will get the right thing. There are two spellings of the method because the Zope 2.x and Zope 3X versions of the package spell it differently. :(

__init__ (
        klass,
        name,
        bases,
        dict,
        )

instancesImplements ( klass )