Support type objects in isinstance().

E.g. isinstance('',types.StringType) will return true now instead of
raising a TypeError exception.  This is for JPython compatibility.

Python/bltinmodule.c

@@ -1627,6 +1627,10 @@ builtin_isinstance(self, args)
 
 	if (!PyArg_ParseTuple(args, "OO", &inst, &cls))
 		return NULL;
+	if (PyType_Check(cls)) {
+		retval = (inst->ob_type == cls);
+	}
+	else {
 		if (!PyClass_Check(cls)) {
 			PyErr_SetString(PyExc_TypeError,
 					"second argument must be a class");
@@ -1640,6 +1644,7 @@ builtin_isinstance(self, args)
 				(PyObject*)((PyInstanceObject*)inst)->in_class;
 			retval = PyClass_IsSubclass(inclass, cls);
 		}
+	}
 	return PyInt_FromLong(retval);
 }