Added a method to teleport entities across worlds.

worldedit-core/src/main/java/com/sk89q/worldedit/extent/clipboard/StoredEntity.java

@@ -68,6 +68,11 @@ abstract class StoredEntity implements Entity {
         return location;
     }
 
+    @Override
+    public boolean setLocation(Location location) {
+        throw new IllegalArgumentException("StoredEntities are immutable");
+    }
+
     @Override
     public Extent getExtent() {
         return location.getExtent();