py: Allow types to be hashable.

Quite natural to have d[int] = handle_int .
diff --git a/py/obj.c b/py/obj.c
index e177782..34a48cc 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -118,6 +118,8 @@
         return (machine_int_t)o_in;
     } else if (MP_OBJ_IS_TYPE(o_in, &mp_type_tuple)) {
         return mp_obj_tuple_hash(o_in);
+    } else if (MP_OBJ_IS_TYPE(o_in, &mp_type_type)) {
+        return (machine_int_t)o_in;
 
     // TODO hash class and instances
     // TODO delegate to __hash__ method if it exists