message: Read 'render_async' parameter from ini file
diff: @@ -354,6 +354,14 @@ struct renderer : viewer_type
  cam.set_focal_distance(fd);
  }
  + // asynchronous rendering
  + bool async = render_async;
  + err = ini.get_bool("render_async", async);
  + if (err == inifile::Ok)
  + {
  + render_async = async;
  + }
  +
  // ImGui menu
  bool hud = show_hud;
  err = ini.get_bool("hud", hud);
  