Lfun:	produce - produce an item on action get

Synopsis:
	object produce(string item)

Description:
	This function is called in a room whenever a person attempts to
	take something. This is currently called before anything else
	(might change).

	The purpose is to enable a room to create an item 'on request'
	by the user (player), usually while also providing description
	of the 'virtual' item through a room item description.

	Produce should check if the string <item> is an id of the item
	to be produced, then clone it and place it in the room (also
	via PRODUCE macro - see 'man lib/PRODUCE') eventually checking
	if there isn't one available yet (PROVIDE macro). Finally it
	should return a pointer to the object, although this is not
	being used (yet), or null if the <item> is not being offered.

	Notice that you should _NOT_ transfer the item into the user's
	inventory. The player takes it via the action 'get'/'take'
	coded in obj/player.

Return value:
	object or 0

Examples:
	Various in Nemesis Village ;-)

	Wizards can 'goto ~kiri/workroom', 'x shelves' and 'get <item>'.

	// from fictional room
	int jacket_taken;
	reset(arg) {
		if (!present("jacket")) jacket_taken = 0;
		[...]
	}

	produce(str) {
		if (str == "jacket" && !jacket_taken && !present("jacket")) {
			jacket_taken = 1;
			jacket = clone_object("lib/armour/jacket2");
			move_object(jacket, this_object());
			return jacket;
		}
	}

Note:
	In 1993 Junky said: I don't know of this function, so i can't
		guarantee that it works.
	In 2015 Kiri says: It works! ;-) Perhaps even before room2.h or
		perhaps at least before the original add_extra_object
		of room2.h ...

	For other possibilities of "searching" see 'man object/search' and
	'man room/do_dig'.

See also: room/add_extra_object, object/id, object/get, object/search, room/do_dig