Bullet cleanup

core/src/mindustry/io/JsonIO.java

@@ -47,6 +47,11 @@ public class JsonIO{
         return json.toJson(object, object.getClass());
     }
 
+    public static <T> T copy(T object, T dest){
+        json.copyFields(object, dest);
+        return dest;
+    }
+
     public static <T> T copy(T object){
         return read((Class<T>)object.getClass(), write(object));
     }