Fix recurrent bug for displaying more than 1000 variants.

[Job van Riet]

If more than 1000 variants are shown, weird graphical results happen. Either put a threshold on 1000 variants per range or fix issue.

[Job van Riet]

Fixed by added turboThreshold to the series. (See http://stackoverflow.com/questions/15921399/highcharts-3-cannot-render-more-than-1000-points-in-one-series)