B01003 - blindfold vs dust vortex

This started out as a change to address the strange sequence of messages if
you remove a blindfold while engulfed in a dust vortex.  That is addressed
by a new function that can be called in such situations.  Calls to this
function were added in all the cases where the can_blnd() engulfing
conditions end as a result of player action.  There are some other cases
that end ucreamed or usleep, but they happen between turns and shouldn't
need extra handling.

While I was at it, I noticed that a unicorn horn or prayer would cure
blindness even while engulfed in a dust vortex.  This is useless, because
you immediately get blind again the next turn.  So, I added checks to avoid
doing this.  Finally, it didn't make sense for eating a carrot to cure your
blindness in these situations either, only for it to return immediately.

src/do_wear.c

@@ -912,8 +912,10 @@ register struct obj *otmp;
 		if (Punished) set_bc(0);
 	    }
 	} else if (was_blind) {
-	    changed = TRUE;	/* !Blind */
-	    You("can see again.");
+	    if (!gulp_blnd_check()) {
+		changed = TRUE;	/* !Blind */
+		You("can see again.");
+	    }
 	}
 	if (changed) {
 	    /* blindness has just been toggled */