Third-party plugins

• external — https://github.com/janschoepke/reveal_external
• menu — https://github.com/denehyg/reveal.js-menu — modified to work with latest Reveal.JS key binding API
• anything — https://github.com/rajgoel/reveal.js-plugins/tree/master/anything
• reveald3 — https://github.com/gcalmettes/reveal.js-d3/