Enable SmartyPants option of Marked when rendering Markdown

[callahad]

marked.setOptions({smartypants: true}); should automatically change straight quotes like "" into nice quotes like “”.

I'd suggest this default to on, since Marked is smart and avoids applying these transformations to code blocks, but I'd be happy with it being more easily configurable, too.

Unfortunately, the version of Marked that's bundled with Reveal has a bug, but updating to the latest Marked release and setting the above option appears to work seamlessly.

[hakimel]

I'm open to adding an option to the markdown plugin for this. Do you want to give it a shot? It would probably make sense to group markdown plugin options inside one object like:

Reveal.initialize({
  markdown: {
    smartypants: true
  }
})

Which the markdown plugin then consumes via Reveal.getConfig().markdown.smartypants.

[legends2k]

It would be good to have @hakimel suggestion, but till then putting this in Reveal.initialize under index.html works:

{ src: 'plugin/markdown/marked.js',
  async: false,
  callback: function() { marked.setOptions({smartypants: true}); } },

[hakimel]

The proposed config option in the comments above was added by @demoneaux in #1765