Changes:

• Add a layout selector to the speaker view with four different options (see example)
• Add ability to pass options to Markdown parser (#1765 by @demoneaux)
• Auto-playing content inside of a fragment now play automatically when the parent fragment is displayed
• Improve indentation correction for code blocks using the data-trim (#1756 by @ jmpp)
• Show an error when an iframe can't be previewed (#1577 by @huxpro)
• Improve accuracy of zoom plugin (#1572 by @jesstelford)
• PDF exports:
  • Add showNotes: 'separate-page' to print speaker notes on separate pages (#1518)
  • Prevent printed pages from overflowing
  • Dispatch a pdf-ready event when the presentation is initialized, laid out and ready to print
  • Add pdfMaxPagesPerSlide config value for controlling how many pages a slide can split into when printing to PDF 55581035228aba9a0d061a6969797327c626b0bf
• Accessibility:
  • Make speaker notes keyboard accessible (#1586 by @jasonkiss)
  • Update disabled attribute on nav buttons for screen reader accessibility (#1586 by @jasonkiss)
  • Don't call out aria-hidden="true" and display: none; elements (#1665 by @Sonaryr)
• New API method Reveal.showHelp() can be called to display a help overlay with keyboard shortcuts #1611
• Increased default font sizes and max presentation scale
• In addition to dispatching a ready event, reveal.js now adds a ready class to the .reveal container that CSS can hook into
• Updated dependencies

Bug fixes:

• Fix disappearing theme background when going fullscreen in Firefox
• Fix occasional null pointer errors related to iframes and slide backgrounds
• Fix blurred content when using the none/fade/slide transitions (#1002)
• Fix incorrect duration calculation for video/audio with playbackRate
• Fix exception when initializing with no slides
• Fix mousewheel-event based navigation when using a trackpad (#1607 by @gera2ld)

And more...