ICS-58: Implement ChartGroup, remove clutter from global namespace and general decoupling

This is a pretty chunky pull.  The main functionality is the new insight.ChartGroup class, which is a container for charts and tables. It handles the events they fire, wiring them up to Crossfilter.

Chart init() has been refactored so you just call chart.draw() (I removed redraw()),which initializes the chart lazily if needed, which is the pattern we've been using more recently.

Charts can be drawn without a container, or the container.draw() can be called if there are multiple charts.

Logic for filter functions has been moved into Dimension, where it fit better.

I had to update all examples (and lots of tests), hence the large number of files changed.
you're right.  The functionality here is more of an array.pluck(property, value) , where you just want to take elements from an object array where they match the input in some way. I'll update the name and parameters to reflect that and maybe stick it in insight.Utils.