Name: set_enter - define a list of adjacent rooms that can be enterd in a room

Syntax:
	#define EXTD_ROOM
	#define ENTER_CMD

	set_enter(string *enter_arr)

Description:
	With the set_enter function you are able to create additional exits
	that are not among the obvious exits.

	The single argument is an array of the following format:
	The first part of the array is the enter id, the second is the file
	name of the enter room and the thrid argument is a flag that shows
	the condition when the entering is successful.

	The flag can be one of the following:

		OPEN         - can be entered all the time
		NIGHT_BARRED - can be entered only if it is day
		DAY_BARRED   - can be entered only if it is night
		CLOSED       - always closed (under construction)
		FUNCTION     - call a function check_enter(room) that returns
		               1 if the room can be entered, else 0

Return value: none

Examples:
	set_enter( ({ "shop", "room/shop", NIGHT_BARRED,
	             "bar", "room/pub1", DAY_BARRED,
	             "guild", "guild/adv/master", OPEN }) );

See also: room/set_read