Rob Flaherty

This adds Zepto compatibility for anyone swapping out jQuery for Zepto. (Fairly common for mobile web apps?) I did some basic testing here and all looks OK: https://dl.dropbox.com/u/1125125/stay/index.html

Sketch 57 remapped the Send Forward and Send Backward shortcuts: Send Backward is now ⌘ [, and Bring Forward is ⌘]. Send to Back is now ⌘ ⌥ [ and...

Currently it's only concerned with vertical scrolling. Makes sense to consider horizontal scrolling too.