Added a mixin specifically for the singleton types (numbers, nil, etc.).
Added a mixin specifically for the singleton types (numbers, nil, etc.).

For a singleton type you define a factory python class who's __new__ returns the builtin type, and then you include PythonSingleton on the class, which turns the singleton object's class into a sort of read-only python object. You have to call python_initialize directly on the singleton's class.

vic/typhon,vic/typhon