update syntax highlight after editing (#210), move markdown and highlight scripts from lib to plugin

Change source from reveal.min.js to reveal.js for testing purposes.

Add nextFragment and previousFragment to the API:
Making it possible to call the methods Reveal.nextFragment()
and Reveal.previousFragment() from »outside«.

Update README.md:
Add the new API Methods Reveal.prevFragment() and Reveal.nextFragment()

Reverted to c34be2e9

new paused mode feature (closes #144), controls and progress DOM elements are no longer required in HTML

woohoo! reveal.js is now HTML5 compliant! 

this is validated using the http://validator.w3.org/ and the http://html5.validator.nu/ services.

this was accomplished using a tad of JavaScript to get around a fullscreen bug.

This also (slightly unintentionally but helpfully) solves a tiny bug with fullscreening in old Opera 11.52 (I think, could be 11.51 or other)

Typo fix: let's -> lets

themes are now available as separate css files under css/theme/, old theme option in config is no longer supported (closes #104)

I gave all the <img>s alt attributes, which makes reveal.js a lot more accessible