Disable click handlers after drag.
Disable click handlers after drag.

Fixes #270

piotr-gawron/pileup.js,snaheth/pileup.js,piotr-gawron/pileup.js,hammerlab/pileup.js,hammerlab/pileup.js,snaheth/pileup.js,piotr-gawron/pileup.js,hammerlab/pileup.js,snaheth/pileup.js,piotr-gawron/pileup.js,snaheth/pileup.js,hammerlab/pileup.js