Document usage of GtkTreeModel in HildonTouchSelector functions
Document usage of GtkTreeModel in HildonTouchSelector functions

Based on a patch by: Xabier Rodriguez Calvar <xrcalvar@igalia.com>

All HildonTouchSelector functions that receive a GtkTreeModel increase
its reference count.

community-ssu/hildon,community-ssu/hildon,community-ssu/hildon,archlinuxarm-n900/libhildon,archlinuxarm-n900/libhildon,archlinuxarm-n900/libhildon