Dumping now respects overwriting of windowprocs functions

* dungeon.c dooverview now uses windowprocs.win_display_menu
* invent.c display_pickinv uses windowprocs.win_display_objs
* end.c container_contents has an added parameter to suppress
the printing of empty bags which was cluttering up the death
menus. container_contents isn't used anywhere else that I can
see and so it probably wasn't necessary to make it an argument,
but it's a little friendlier that way.