End event swipe

Add swipe property to end and inertiastart events …

```
{
  left    : bool,
  right   : bool,
  up      : bool,
  down    : bool,
  angle   : number (degrees),
  speed   : number (pixels/sec),
  velocity: { x: number (pixels/sec), y: number (pixels/sec) }
}
```

A diagonal swipe would have two direction properties be true.

Closes #30