message: use the umd polyfill instead of the one vendored
diff: <!--<div class="spacer"></div>-->
  </section>
  <!-- script -->
  - <script src="/assets/vendor/browser-polyfill.js"></script>
  + <script src="/assets/polyfills.js"></script>
  <script src="/assets/vendor/IO/load_file.js"></script>
  <script src="/assets/vendor/IO/save_file.js"></script>
  <script src="/assets/vendor/panel/js/context_menu.js"></script>
  