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/worn.c

@@ -321,7 +321,7 @@ mon_adjust_speed(struct monst *mon,
         if (petrify) {
             /* mimic the player's petrification countdown; "slowing down"
                even if fast movement rate retained via worn speed boots */
-            if (flags.verbose)
+            if (Verbose(3, mon_adjust_speed))
                 pline("%s is slowing down.", Monnam(mon));
         } else if (adjust > 0 || mon->mspeed == MFAST)
             pline("%s is suddenly moving %sfaster.", Monnam(mon), howmuch);