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/eat.c

@@ -1638,7 +1638,9 @@ register struct obj *otmp;
 		    you_unwere(TRUE);
 		break;
 	    case CARROT:
-		make_blinded((long)u.ucreamed,TRUE);
+		if (!u.uswallow ||
+		    !attacktype_fordmg(u.ustuck->data, AT_ENGL, AD_BLND))
+		    make_blinded((long)u.ucreamed,TRUE);
 		break;
 	    case FORTUNE_COOKIE:
 		outrumor(bcsign(otmp), BY_COOKIE);