Added cancelAnimationFrame utility

Like its sister method raf, craf cancels a previously registered frame.
It basically works the same way as setTimeout/clearTimeout
Introducing symphonyAffix

This little plugin makes it easy to create elements that "follow" the scroll,
up to a certain point (container constraint).
Creating the affix for expand all / collapse all

This makes the two links follow the scroll when they get out of sight.

The plugin uses fixed positioning in order to avoir full page paints.
Removed double click action

This feature has been broken in 2.4.

Users can now expand / collapse all usign the new affix plugin, so
there is now use of fixing it.