Enables "pull to refresh" when the user specified scroll="bidirectional", updated the multidirectional example to add pull-to-refresh
In bidirectional mode, I changed it so that if you use the mouse scroll wheel it always scrolls the grid vertically vs. horizontally (which is the current default), which seems more natural
Fixes an issue where if you perform a horizontal swipe gesture on a trackpad without first scrolling vertically, the horizontal swipe does not scroll the grid.
This commit includes: