corpse_xname overhaul (trunk only)

Extend the capabilities of corpse_xname() so that various callers can
be simplified.  It can how handle an article prefix, effectively turning it
into corpse_doname() (not quite; still need doname() to see a count when
quantity is more than one, or to see bless/curse state).  It can also handle
inclusion of adjectives like "partly eaten" or "bite-covered".  For unique
monsters those come out in the form
  the Chromatic Dragon's partly eaten corpse
instead of the old
  partly eaten Chromatic Dragon corpse
[so wishing probably needs to be taught about potentially finding a monster
name before assorted adjectives such as blessed; also, name_to_mon() needs
to learn how to cope with the possessive suffix].

     A sizeable chunk of this patch deals with consolidating some of the
redundant "petrified by a cockatrice corpse" handling.  It may be possible
to consolidate all remaining instances together since they're quite similar,
but I didn't think about that until just now and I want to get this patch
over with.

src/dig.c

@@ -1538,7 +1538,8 @@ long timeout;	/* unused */
 	    y = obj->oy;
 	} else if (in_invent) {
 	    if (flags.verbose) {
-		char *cname = corpse_xname(obj, FALSE);
+		char *cname = corpse_xname(obj, (const char *)0, CXN_NO_PFX);
+
 		Your("%s%s %s away%c",
 		     obj == uwep ? "wielded " : nul, cname,
 		     otense(obj, "rot"), obj == uwep ? '!' : '.');