UIScrollView category for scrolling to edges and pages.
✓ Checks if scroll view is scrolled to a given edge.
scrollView.isScrolled(to edge: .top)
✓ Scrolls to edges.
scrollView.scroll(to: .left)
scrollView.scroll(to: .right, animated: true)
✓ Scrolls to pages.
scrollView.scroll(to: .horizontal(index: 3))
scrollView.scroll(to: .vertical(index: 5), animated: true)
✓ Snap to axes
scrollView.snap(to: .vertical, animated: true).