implementing icon-based toolbar on the upper right and altering the what...

Implementing the icon-based toolbar from this mockup image (was it ever included in the issues tracker?):

![mockup01](https://f.cloud.github.com/assets/2553268/322040/207de004-9a22-11e2-9add-ce4ae0ba2b29.png)

... and changing the what-is-this.js script to make the info box drop down when a user clicks the "?" icon. Hiding the teaser element (which used to show up) is a quick hack and not actually removed from the code.

The other two icons - "settings" and "share" - currently do nothing.