granular verbose message suppression mechanics

Switch to using a macro invocation Verbos(n, s) in place of the
flags.verbose checks.

Provide the mechanics for individual suppression of any of the
existing messages that were considered verbose.

Mechanics only - this code update does not provide any means of
setting the suppression bits.

iflags.verbose = 0
is still a master suppression of all the verbose messages.

iflags.verbose = 1
turns on the verbose messages only for those whose suppression
bit is 0 (not set).

src/steal.c

@@ -751,7 +751,7 @@ relobj(
     } /* isgd && has gold */
 
     while ((otmp = (is_pet ? droppables(mtmp) : mtmp->minvent)) != 0) {
-        mdrop_obj(mtmp, otmp, is_pet && flags.verbose);
+        mdrop_obj(mtmp, otmp, is_pet && Verbose(1, relobj));
     }
 
     if (show && cansee(omx, omy))