Reset Unsorted flag only after sorting has been fully finished

This not only seems more correct but might also fix #711

src/game/object/C4GameObjects.cpp

@@ -482,13 +482,13 @@ void C4GameObjects::ResortUnsorted()
 		{
 			// readd to main object list
 			Remove(cObj);
-			cObj->Unsorted=false;
 			if (!Add(cObj))
 			{
 				// readd failed: Better kill object to prevent leaking...
 				Game.ClearPointers(cObj);
 				delete cObj;
 			}
+			cObj->Unsorted=false;
 		}
 	}
 }