view gradually degrades)

	Now the menu-updating code does not run while rubberband
	selecting (but does run immediately thereafter).

	* libnautilus-extensions/nautilus-icon-container.h:
	* libnautilus-extensions/nautilus-icon-container.c:
	(start_rubberbanding), (stop_rubberbanding),
	(nautilus_icon_container_initialize_class): New signals
	"band_select_started" and "band_select_ended" emitted
	just when you'd expect.

	* src/file-manager/fm-directory-view.h:
	Prototypes for new functions (intended to be called only
	by subclasses) fm_directory_view_start_batching_selection_changes
	and fm_directory_view_stop_batching_selection_changes.

	* src/file-manager/fm-directory-view.c:
	Added details fields: guint batching_selection_level,
	gboolean selection_changed_while_batched, gboolean
	menu_states_untrustworthy
	(selection_contains_one_item_in_menu_callback),
	(selection_not_empty_in_menu_callback): New helper functions
	that report if the selection matches expectations and complain
	via g_warning if they don't match and we trust the menu state.
	(open_callback), (trash_callback), (duplicate_callback),
	(create_link_callback),	(open_properties_window_callback):
	Use these new helper functions to verify that the menu state
	matches expectations but not crash if it doesn't.

	(schedule_update_menus): Change timeout back to idle now that
	it isn't affecting the band-select case; mark menu states as
	untrustworthy.
	(fm_directory_view_update_menus): mark menu states as
	trustworthy.

	(fm_directory_view_notify_selection_changed): If we're batching
	selection changes, remember that the selection changed; otherwise,
	do the work that you only do when not batching (update menus).

	(fm_directory_view_start_batching_selection_changes): Increment
	the batching level counter.
	(fm_directory_view_stop_batching_selection_changes): Decrement
	the batching level counter. If it reaches zero, and the selection
	changed while batched, call notify_selection_changed.

	* src/file-manager/fm-icon-view.c:
	(band_select_started_callback): start batching selection changes.
	(band_select_ended_callback): stop batching selection changes.
	(create_icon_container): connect to band_select_started and
	band_select_ended signals of icon container.