Add swipe property to end and inertiastart events

{
  left    : bool,
  right   : bool,
  up      : bool,
  down    : bool,
  angle   : number (degrees),
  velocity: { x: number (pixels/sec,) y: number (pixels/sec) }
}

A diagonal swipe would have two direction properties be true.
Add swipe demo
Use prevEvent velocity to calculate angle

Snapping and restrictions can lead to an incorrect angle when dx, dy
is used
Fire '*inertiastart' before calculating trajectory
Merge branch 'end-event-swipe'
Bump version to 1.0.18