SC.TouchScrollerView => SC.OverlayScrollerView

[Dave Porter]

With an eye towards removing bogus mouse/touch differentiations from the frameworks, I'm going to rename SC.TouchScrollerView to SC.OverlayScrollerView. It's mostly a symbolic gesture, but it makes the documentation smoother, removing the need for me to say things like "yeah it's called touch but no you can use it whenever you like, via this hacky-looking but legitimate override."

I'm keeping a copy of the class on the old name by way of backwards-compatibility of course.

Thoughts or objections?

Cheers

Dave