SDLPP: make copySelf actually copy everything

sdlpp/sdlpp_rectrenderer.cpp

@@ -139,9 +139,12 @@ void RectangleRender::centerX() {
     updateSizeAndPosition();
 }
 std::shared_ptr< RenderObject > RectangleRender::copySelf() {
-    // TODO ACTUALLY copy, don't just copy pointers to textures and whatnot,
-    // create new textures!!!
-    return std::make_shared< RectangleRender >( *this );
+    auto ret = std::make_shared< RectangleRender >( *this );
+    copyTo(ret);
+    return ret;
+}
+void RectangleRender::copyTo(std::shared_ptr<RenderObject> other) {
+    RenderObject::copyTo(other);
 }
 std::string RectangleRender::getColor() const {
     return color;