Clean up Renderers.

First, removed the dataSelection property. In most cases, there
wasn't much point in hanging on to the selection. Exception: bar
renderers, which used the selection to support highlighting bars.

In addition, removed some unused fields and fields that were saved off,
but not used outside of the _paint() call.

Close #500.
Merge pull request #505 from palantir/500-renderer-cleanup

Clean up Renderers.
Have LineRenderer extend AreaRenderer

By default, AreaRenderer's stroke color is set to "none", and LineRenderer's
fill color is set to "none".

Close #501.
Close #506.
changed callback api
Merge pull request #479 from palantir/legend-toggle

Legend toggle
Scope WordWrapUtils vars inside the module rather than polluting global namespace
Update built files
Merge pull request #507 from palantir/area-line-renderer

Have LineRenderer extend AreaRenderer
Release version 0.14.2
Merge branch 'master' into hover-legend
changed callback api for HoverLegend