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/artifact.c

@@ -1300,7 +1300,7 @@ Mb_hit(struct monst *magr, /* attacker */
             shieldeff(youdefend ? u.ux : mdef->mx,
                       youdefend ? u.uy : mdef->my);
         }
-        if ((do_stun || do_confuse) && flags.verbose) {
+        if ((do_stun || do_confuse) && Verbose(0,Mb_hit)) {
             char buf[BUFSZ];
 
             buf[0] = '\0';