fixes hakimel/reveal.js#3231

Fixes https://github.com/hakimel/reveal.js/issues/3315

Co-authored-by: Giacomo Zinetti <giacomo.zinetti@giko.it>

fix issue where auto-animate did not work when jumping three or more slides (i.e. longer than the view distance)

refactor hash parsing, fixes issue with autoplaying media not starting from internal links on mobile devices

So far, multiple notes per slide are only supported if they are
attached to fragments (without fragments, only the first aside notes
element on a slide is displayed).  With this commit, the contents of
all notes on a slide are displayed (except for fragments with notes,
for which, as before, only each fragment's first/single note is
displayed).

new shortcuts; alt+arrow key skips fragments, shift+arrow key jumps to last slide in the given direction #1105

fixes #2635