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)

always use css transforms for presentation scaling (zoom has too many quirks even if it is slightly sharper on ldpi displays)

fix fullscreen issues; correct size in Safari, auto-focus presentation when entering fullscreen #3080

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

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

When embedding reveal in a website, this will help avoid global variable conflicts with other frameworks that use global styles via variables.