Bugfixes to sorting and averaging as support to my front-page examples

- I updated how sorting works to fix the examples I was using on the front page.
- I added a points() getter/setter to LineSeries in response to Dan asking if the points on lines could be disabled. 
- I refactored how averages are calculated to fix a bug I noticed with mean values after filtering;
- chart.draw() was being called twice in drawCharts, so I removed the extra call.

The insight.js.zip is making it quite hard for me to rebase other's merges onto my ongoing work, so I couldn't squash my commits into one.