SET&QUERY - stethoscope.c

Usual defined LFUN's:
query_weight(),query_value().

query_listening(): This returns the object that is listened to by the player
                   using the stethoscope. 0 if there is no object. The object
                   listened to usually is another player, but objects that
                   have the function use_stethoscope defined will also be
                   listened to.
