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/explode.c

@@ -515,7 +515,7 @@ explode(
     if (uhurt) {
         /* give message for any monster-induced explosion
            or player-induced one other than scroll of fire */
-        if (flags.verbose && (type < 0 || olet != SCROLL_CLASS)) {
+        if (Verbose(1, explode) && (type < 0 || olet != SCROLL_CLASS)) {
             if (do_hallu) { /* (see explanation above) */
                 do {
                     Sprintf(hallu_buf, "%s explosion",