WHICH maps a room's visible exits to the face of a compass.
(Up and Down appear on the right side of the "compass")
WHICH looks for N, S, E, W, U, D, NE, NW, SE, SW in an exit's
synonym list. If it finds it, and the exit is visible, then it
will appear on the compass face, given up to three lines of
thirty characters each, to display the exit name.