fixed the prev/next sibling delayed hiding code: it now works and is again simpler, thanks to the last changes to the CSS for past-1/future-1 in the previous commit
fixed the prev/next sibling delayed hiding code: it now works and is again simpler, thanks to the last changes to the CSS for past-1/future-1 in the previous commit

GerHobbelt/reveal.js,GerHobbelt/reveal.js,GerHobbelt/reveal.js