Add gobject-introspection annotations

Add annotations such as (transfer-none) (out) (element-type ClutterActor),
and so forth to the doc comments as appropriate.

The annotations added here are a combination of the annotations previously
in gir-repository for Clutter and annotations found in a review of all
return values with that were being parsed with a transfer of "full".

http://bugzilla.openedhand.com/show_bug.cgi?id=1452

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>

clutter/clutter-path.c

@@ -936,7 +936,7 @@ clutter_path_get_node (ClutterPath     *path,
  * list to become invalid so you should copy them if you want to keep
  * the list.
  *
- * Return value: a list of nodes in the path.
+ * Return value: (transfer container) (element-type ClutterPathNode): a list of nodes in the path.
  *
  * Since: 1.0
  */