dialog be parented on the NautilusWindow from whence
	it came.

	* libnautilus-extensions/nautilus-program-choosing.h:
	* libnautilus-extensions/nautilus-program-choosing.c:
	(nautilus_launch_application_parented): Removed this function
	(nautilus_launch_application): Made this function take a
	parent (can be NULL, but better not to be).

	* src/file-manager/fm-directory-view.c:
	(fm_directory_view_launch_application): Remove "_parented"

	* src/nautilus-sidebar.c:
	(nautilus_sidebar_get_window): New helper function to get
	enclosing window.
	(command_button_callback),
	(nautilus_sidebar_chose_application_callback): Pass parent
	window to nautilus_launch_application.