Html5 data attributes2

To be fully HTML5 complaint, it should be easy to allow the data- attributes. So I built this in the library.

It's easier to enable and also it saves a lot of events compared to the 'onRemove event solution' 

Don't know why this cannot be merged automatically. But the LF think is a bit annoying at my site (Visual studio changes to CRLF so I have to fix every file after each change)