Swipe implementation

[JayPanoz]

Currently there is no swipe listener in EPUBNavigatorListeners, while it could be useful for app developers i.e. setting an immersive mode/hiding the UI when swiping.

It’s not as easy as handling a callback though, since a swipe event could then fire without the position changing for instance, which isı't necessarily what may be expected. We need to define what a swipe event is, and what it should cover.

Note there are talks about redesigning these so that they work in a way similar to adding/removing event listeners happening in parallel.