or switches to viewers so that when bugs 1053 and 1072 are
	fixed it will be trivial to finish this code.

	* libnautilus-extensions/nautilus-gtk-extensions.h,
	* libnautilus-extensions/nautilus-gtk-extensions.c:
	(nautilus_gtk_signal_connect_free_data_custom): New function
	to specify a GtkDestroyNotify function when connecting to a
	signal, without having to specify everything else in
	gtk_signal_connect_full.
	(nautilus_gtk_signal_connect_free_data): Changed to call
	nautilus_gtk_signal_connect_free_data_custom.

	* libnautilus-extensions/nautilus-view-identifier.c:
	(nautilus_view_identifier_copy): Made it handle NULL parameter.

	* src/file-manager/fm-directory-view.c:
	(application_launch_parameters_new),
	(application_launch_parameters_free),
	(viewer_launch_parameters_new),
	(viewer_launch_parameters_free): New helper functions for
	dealing with the structs needed to launch an app or viewer.

	(fm_directory_view_launch_application): New wrapper for
	nautilus_launch_application that will let us handle
	errors in a single place.

	(switch_location_and_view): New bottleneck function or going
	to a particular location with a particular viewer. This
	doesn't work yet (bug 1053) and it currently puts up a
	message box telling the user so.

	(fm_directory_view_chose_application_callback),
	(fm_directory_view_chose_component_callback), (choose_program),
	(choose_application), (choose_component),
	(launch_application_from_menu_item), (view_uri_from_menu_item),
	(add_application_to_gtk_menu), (add_component_to_gtk_menu),
	(create_open_with_gtk_menu), (bonobo_launch_application_callback),
	(add_application_to_bonobo_menu),
	(bonobo_open_location_with_viewer_callback),
	(add_component_to_bonobo_menu):
	Reworked to pass around launch_parameters structs instead of other
	bits and pieces of info. Darin will be happy to know that info
	needed for menu item callbacks is now bundled up and passed as
	the callback data instead of sneaking in as gtk_object_data.