message: add menu item to recenter camera
diff: @@ -1477,6 +1477,12 @@ void MainWindow::buildMainMenuView()
  showLightEditor = true;
  if (ImGui::MenuItem("Camera...", "", nullptr))
  showCameraEditor = true;
  + if (ImGui::MenuItem("Center camera", "", nullptr)) {
  + arcballCamera.reset(
  + new ArcballCamera(frame->child("world").bounds(), windowSize));
  + updateCamera();
  + }
  +
  ImGui::Separator();
  if (ImGui::MenuItem("Geometry...", "", nullptr))
  showGeometryViewer = true;
  