Bug fix. Cleanup.

* Cleaned up old global variables.
* Moved declaration of start / end range variables to top of file.
* The blue "paused" bar for the timeline now is only visible when you
are actually paused.
* drawVisualization() is now setupTimeline()
* setupTimeline() now invoked on document ready rather than onload
* Fixed a bug that caused erratic jumping when clicking on the timeline.
This was caused by duplicated code in the jumpToNearestEvent() function
drawVisualization() now no longer needs to be called via onload