Fixed cellrenderer model column combobox chooser.
If treeview model is a filter or a sort model we need to walk up until
we find a tree or list store which is where glade have defined the model columns.
Fix issue with numeric property editors.
We have to make sure  glade_eprop_numeric_load() is not called during
glade_eprop_numeric_force_update() to prevent gtk_spin_button_set_value()
changing the the value the user is trying to input.
Fixed identation spaces in function declarations.