(mult, player_coms): Command `mult' is disabled since 4.0.0 ('96), and

its code is obviously not in working order.  Remove.
(minmult, maxmult, configkeys): Unused configuration parameters,
remove.
(tradedesc): Remove code related to mult that had no effect.
(multread, commread, commwrite, commamt, commset, multset, commprice):
Dangerous, because code bypasses ef_read() & friends, remove.
(diss): Commodity cleanup uses the above, remove.  Command is disabled
and unlikely to work anyway.

src/lib/global/constants.c

@@ -156,8 +156,6 @@ double bankint = 0.25;		/* bank interest rate (dt * bars) */
               charged (price paid * buytax).
    Not perfect, but it works. :) */
 
-double minmult = 0.5;		/* minimum trade mulitple */
-double maxmult = 10.0;		/* maximum trade multiple */
 double tradetax = 0.99;		/* Tax charged on trade */
 double buytax = 1.0;		/* Tax charged on market purchases */
 int startmob = 127;		/* Sanctuary starting mobility */