Add PyMethod_Function(), PyMethod_Self(), PyMethod_Class() back.

While not even documented, they were clearly part of the C API,
there's no great difficulty to support them, and it has the cool
effect of not requiring any changes to ExtensionClass.c.

Include/classobject.h

@@ -47,6 +47,10 @@ extern DL_IMPORT(PyObject *) PyInstance_New(PyObject *, PyObject *,
 extern DL_IMPORT(PyObject *) PyInstance_NewRaw(PyObject *, PyObject *);
 extern DL_IMPORT(PyObject *) PyMethod_New(PyObject *, PyObject *, PyObject *);
 
+extern DL_IMPORT(PyObject *) PyMethod_Function(PyObject *);
+extern DL_IMPORT(PyObject *) PyMethod_Self(PyObject *);
+extern DL_IMPORT(PyObject *) PyMethod_Class(PyObject *);
+
 /* Macros for direct access to these values. Type checks are *not*
    done, so use with care. */
 #define PyMethod_GET_FUNCTION(meth) \

Objects/classobject.c

@@ -106,6 +106,36 @@ PyClass_New(PyObject *bases, PyObject *dict, PyObject *name)
 	return (PyObject *) op;
 }
 
+PyObject *
+PyMethod_Function(PyObject *im)
+{
+	if (!PyMethod_Check(im)) {
+		PyErr_BadInternalCall();
+		return NULL;
+	}
+	return ((PyMethodObject *)im)->im_func;
+}
+
+PyObject *
+PyMethod_Self(PyObject *im)
+{
+	if (!PyMethod_Check(im)) {
+		PyErr_BadInternalCall();
+		return NULL;
+	}
+	return ((PyMethodObject *)im)->im_self;
+}
+
+PyObject *
+PyMethod_Class(PyObject *im)
+{
+	if (!PyMethod_Check(im)) {
+		PyErr_BadInternalCall();
+		return NULL;
+	}
+	return ((PyMethodObject *)im)->im_class;
+}
+
 static PyObject *
 class_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {