Name: add_item/change_item/remove_item - manipulations on room items

Synopsis:
	#include <room2.h>
	status add_item(id, desc, type);
	status change_item(id, desc, type);
	status remove_item(id, type);

Description:
	Adding/changing/removing a room item.

Note:
	Some information about these functions can be found on page 17 in
	the tutorial of advanced room coding ('goto /guild/adv/inner3') or
	via https://nemesis.de/lpc/doc/room2/page17 . I (Kiri) don't like
	this possibility to alter room items, so I don't recommend them.
	The "@@func@@" feature works much better, also described on page 17
	(upper part) of the tutorial and in 'man room/set_items'.

See also: room/set_items, room2/page17