linkedin/hopscotch — pull request #137 by kate2753 (2014-12-02 05:15:54+00:00)
Title: GH-40 NextOnTarget Click event not always removed

Remove on click listener with nextOnTargetClick callback for following cases:
* changing step with nextStep or prevStep call (removeEvtListener in changeStep function)
* changing step directly via showStep call (removeEvtListener in showStepHelper function)
* ending tour via closeTour call or clicking on close button (removeEvtListener inside endTour function)

Additionally, removing few unused variables throughout the code.