Escaped the arrow on Next to make it 'ASCII' compatible
Added ability to define a callback on skip
Merged latest from source and removed own callback
Merged latest from source
Used data-intro as prefix
set intro step to zero at the end of introduction
Fixed bug with data-intro-*
Fix position relative/absolute bug
Redesign buttons + add previous button to tooltip buttons
Add buttons copyright
Merge branch 'master' of https://github.com/usablica/intro.js
Merge branch 'master' into upstream