Pass refresh errors from the very bottom of the loading sequence up to the top

Pass refresh errors from the very bottom of the loading sequence up to the top
	(start_loading_current_folder): Check if the folder to be loaded
	is non-native for the local_only=TRUE case; if so, return an error
	as we are configured to load only local folders.
	(reload_current_folder): Pass on errors from
	start_loading_current_folder().  Tighten the preconditions, as we
	are sure that we can only receive non-NULL folder-files to load.
	(refresh_current_folder_and_file_part): Pass on errors from
	reload_current_folder().  At the very end, assert the invariant
	described above.

Signed-off-by: Federico Mena Quintero <federico@novell.com>
svn path=/trunk/; revision=22182