#adjust tweaks (trunk only)

     Allow '#' as a destination slot if you've given '#' as the source
and there aren't any available inventory letters, making it possible to
use doorganize()'s feature of merging compatible items into one slot even
when that slot is #.  ('#' won't work as a destination when the source is
from a regular letter.  If the player wants to swap something in letter
slot x with whatever is in the # slot, he'll have to use # -> x rather
than x -> #.)

     Also, a post-3.4.3 change made it possible to produce an inventory
that used duplicate letters.  Giving a count while specifying the source
slot splits the source object.  But the extra '?' choice added to show
inventory letters in use didn't undo the split if player hit ESC to quit
early instead of specifying a destination slot.

     Lastly, don't prompt forever if the user doesn't give a valid
destination letter; give up after 5 attempts.

src/invent.c

@@ -2790,8 +2790,8 @@ int
 doorganize()	/* inventory organizer by Del Lamb */
 {
 	struct obj *obj, *otmp, *splitting, *bumped;
-	register int ix, cur;
-	register char let;
+	int ix, cur, trycnt;
+	char let;
 	char alphabet[52+1], buf[52+1];
 	char qbuf[QBUFSZ];
 	char allowall[3];	/* { ALLOW_COUNT, ALL_CLASSES, 0 } */
@@ -2838,34 +2838,34 @@ doorganize()	/* inventory organizer by Del Lamb */
 	/* compact the list by removing all the blanks */
 	for (ix = cur = 0; alphabet[ix]; ix++)
 		if (alphabet[ix] != ' ') buf[cur++] = alphabet[ix];
+	if (!cur && obj->invlet == NOINVSYM) buf[cur++] = NOINVSYM;
 	buf[cur] = '\0';
 	/* and by dashing runs of letters */
 	if(cur > 5) compactify(buf);
 
 	/* get 'to' slot to use as destination */
 	Sprintf(qbuf, "Adjust letter to what [%s]%s?", buf,
 		invent ? " (? see used letters)" : "");
-	for (;;) {
+	for (trycnt = 1; ; ++trycnt) {
 	    let = yn_function(qbuf, (char *)0, '\0');
 	    if(let == '?' || let == '*') {
-		char ilet = display_used_invlets(splitting ? obj->invlet : 0);
-		if(!ilet) continue;
-		if(ilet == '\033') {
-			pline(Never_mind);
-			return 0;
-		}
-		let = ilet;
+		let = display_used_invlets(splitting ? obj->invlet : 0);
+		if (!let) continue;
+		if (let == '\033') goto noadjust;
 	    }
 	    if (index(quitchars, let) ||
 		    /* adjusting to same slot is meaningful since all
 		       compatible stacks get collected along the way,
 		       but splitting to same slot is not */
 		    (splitting && let == obj->invlet)) {
+ noadjust:
 		if (splitting) (void) merged(&splitting, &obj);
 		pline(Never_mind);
 		return 0;
 	    }
-	    if (letter(let) && let != '@') break;	/* got one */
+	    if ((letter(let) && let != '@') || index(buf, let))
+		break;	/* got one */
+	    if (trycnt == 5) goto noadjust;
 	    pline("Select an inventory slot letter.");	/* else try again */
 	}