No visible effect yet.

	* libnautilus-extensions/nautilus-bookmark.h:
	Added nautilus_bookmark_get_file prototype, not yet
	called or implemented.

	* libnautilus-extensions/nautilus-file.h,
	* libnautilus-extensions/nautilus-file.c:
	(nautilus_file_check_if_ready): New function, does
	nothing yet.

	* libnautilus-extensions/nautilus-icon-factory.h:
	Added nautilus_icon_factory_is_icon_ready_for_file
	prototype, not yet called or implemented.

	* src/nautilus-window-menus.c:
	(nautilus_window_initialize_bookmarks_menu),
	(nautilus_window_initialize_go_menu),
	(nautilus_window_remove_bookmarks_menu_callback),
	(nautilus_window_remove_go_menu_callback),
	(refresh_bookmarks_menu),
	(refresh_bookmarks_menu_idle_callback),
	(schedule_refresh_bookmarks_menu), (refresh_go_menu),
	(refresh_go_menu_idle_callback), (schedule_refresh_go_menu):
	Made the code that rebuilds the Go and Bookmarks menus when
	there's been a change to the bookmarks use idle handling to
	batch up requests. This will be important when bookmarks
	broadcast updates for their icons.

	* src/nautilus-window-private.h: Defined NautilusWindowDetails
	struct. We should eventually migrate all of the fields
	of NautilusWindow in here, but I didn't do that now.
	Added two fields used by bookmark-menu-updating code.
	* src/nautilus-window.h: Made a details field using
	NautilusWindowDetails.

	* src/nautilus-window.c:
	(nautilus_window_init): Create details field.
	(nautilus_window_destroy): Clean up any pending idle bookmark
	refreshing stuff.