ensure unique costume names when copying costumes via d&d

gui.js

@@ -5374,6 +5374,7 @@ SpriteIconMorph.prototype.copyStack = function (block) {
 
 SpriteIconMorph.prototype.copyCostume = function (costume) {
     var dup = costume.copy();
+    dup.name = this.object.newCostumeName(dup.name);
     this.object.addCostume(dup);
     this.object.wearCostume(dup);
 };

history.txt

@@ -2208,4 +2208,4 @@ ______
 140718
 ------
 * Lists: incorporate Brian’s adhoc fixes, thanks, Brian!
-* GUI: Use new mechanism for unique costume names on the paint editor, renamed costumes
+* GUI: Use new mechanism for unique costume names on the paint editor, renamed costumes and costumes dragged and dropped onto sprite icons