v3 Playground: Presentation Mode Plugin

[orta]

Build as a separate repo, to enforce the separation of concerns and ensure that the plugin infra (which is already in and used for all the current sidebar tabs) works well with external apps.

Need to add a way to declare that you want to use a custom plugin into the options section (and I'd probably add this one in the list, off by default)

Enabling it would add a new sidebar menu: "Present" which offers a bunch of settings. The key one being either a link to a markdown file (or a markdown gist?)

You write a markdown file a bit like like this file: https://gist.github.com/orta/d7dbd4cdb8d1f99c52871fb15db620bc

Which takes a lot of ideas from https://www.deckset.com

For example:

• A slide with just an image centers it

• A slide with a H2 and some Ps
  

• A slide with H2s and just LIs

Then when the slide is just code, that code is set into monaco, and you're good to go

Slides styles I always use and would need syntax for:

Showinging blocks of info:

Highlighting a screenshot, with a title:

[orta]

https://github.com/hakimel/reveal.js looks like a reasonable foundation

[orta]

Done: #204