Various changes to tidy up code and maximize vertical space for histograms.  Also, moved around code that hides/displays visual elements for stats based on events so that old stats don't show when user has selected a new reference or region.  Made some small changes to get tooltip working in various charts.
Merge branch 'master' into gh-pages

* master:
  Various changes to tidy up code and maximize vertical space for histograms.  Also, moved around code that hides/displays visual elements for stats based on events so that old stats don't show when user has selected a new reference or region.  Made some small changes to get tooltip working in various charts.