…issue

fix and refine:
1. Add the event as a gesture property, and can be exposed to consumer. E.g.: rc-swipeout need using event to prevent scroll when touch moving.
2. Fixed a bug: panMove event could be invoked by unavailable touches. Look at the image for intuitional understanding: https://gw.alipayobjects.com/zos/rmsportal/nJviUPgzjtrUGCKrvUCz.gif.