re-created unprefixed version of reveal.css automatically using autoprefixer, to facilitate merging of changes to it

according to README, I don't include reveal.min.js.
Hence I believe it makes sense to not include reveal.min.css either.
Hence, examples added in index.html can give the feeling that they don't work yet.

.slides>section and .slides>section>section set the font-weight to
"normal". This overrides any font-weight setting a theme may set at
the body or .reveal level, and requires a theme author to also
specifically set the font-weight for .slides>section and
.slides>section>section. That's tedious and also counterintuitive.

Adopt a saner default by setting the font-weight to inherit.

move the slide-number out of the controls to a proper position and little fix to the updating event.

the *.min.js didn't chaged yet.

use 'url()'-free path when specifying parallax image, refactor so that parallax is applied to background class, remove unused attributes #595

modified:   css/reveal.css
modified:   css/reveal.min.css
modified:   plugin/leap/leap.js