SwapView fixes

- changed swipe implementation: set transforms and do transitions fully in JavaScript instead of modifying CSS rules dynamically (which causes security errors when loading CSS cross-domain, for example when the deliteful lib is hosted on a different server than the web app);
- changed default swapThreshold from 0.5 to 0.25;
- handle "pointercancel" events to fix problems when user clicks a scrollbar inside the SwapView on desktop;
- changed touch-action from "none" to "pan-y" to allow vertical scrolling inside the SwapView (for example, a scrollable list).