Square bullet labels

* changes labelgroup.js to use squares instead of circles for bulleted/numbered/lettered labels
* bullets start on specified point, instead of having their centers on specified point
* updating some styling to match square bullets and new design in widgets.css
* update examples which use labels
Cheap demo of zoom
* GlobalEnergyUse has a line in the handler to completely remove the graph, and draw a new one.  This is because we don't have redraw on axes.
* Added example to toc-structure.js
* also adding an example file that Chad made, but not in book.
Merge branch 'upstream/LeslieDemoBranch'