* Evolution-Shell.idl: add "cancel" to FolderSelectionListener.
* evolution-shell-client.c (impl_FolderSelectionListener_cancel):
Implement cancel (set *uri and *physical_uri to NULL).
(evolution_shell_client_user_select_folder): document %NULL uri
and physical_uri return values.
* e-shell.c (folder_selection_dialog_clicked_cb): If the user
clicked "Cancel" or used the wm to close the dialog, call _cancel
instead of _selected.
svn path=/trunk/; revision=3831
