HTTPS relevant links on README

Bug fix: spelling errors

Allowing autoplay in data-background-iframe for audio and video elements

Add forgotten element to Table of Contents

Add mobileViewDistance config key

update minimal nodejs version in readme

Tweak to MathJax example

Update package.json for node 12 support

docs: fix typo

simple node-sass update which fixes this issue

Added a missing comma and used an actual macro so that the MathJax example runs right out of the box upon a copy/paste.

Fix plugin documentation regarding init-Promises

add missing comma to MathJax example in README

It was restricted by «Autoplay Policy Changes»: https://developers.google.com/web/updates/2017/09/autoplay-policy-changes#iframe

Fix arrow down navigation on touch devices

When using the totalTime-based pacing calculation, a presenter may
inadvertently set totalTime and per-slide data-timing attributes in
such a way that the pacing time for some slides is impossibly low or
even negative.

Add a check to ensure that the pacing on a slide never falls below a
configurable minimum, defaulting to 0. Display an alert if the
pacing for any slide(s) falls below the threshold.