Improve repaint functions

It is sometimes useful to be able to have better control on when a
repaint function is called. Currently, all repaint functions are called
prior to the stages update phase of the frame processing.

We can introduce flags to represent the point in the frame update
process in which we wish Clutter called the repaint function.

As a bonus, we can also add a flag that causes adding a repaint function
to spin the master clock.

clutter/clutter-main.h

@@ -122,6 +122,10 @@ guint                   clutter_threads_add_timeout_full        (gint
 guint                   clutter_threads_add_repaint_func        (GSourceFunc    func,
                                                                  gpointer       data,
                                                                  GDestroyNotify notify);
+guint                   clutter_threads_add_repaint_func_full   (ClutterRepaintFlags flags,
+                                                                 GSourceFunc    func,
+                                                                 gpointer       data,
+                                                                 GDestroyNotify notify);
 void                    clutter_threads_remove_repaint_func     (guint          handle_id);
 
 void                    clutter_grab_pointer                    (ClutterActor  *actor);