Introduced to display boxplots
Altered 5-number summary code

This code should be more robust.
Added highcharts-more library

Required for box plots
Fix for bug that prevented frequencies

Salstat had problems calculating frequencies. This fix should allow
them to be calculated and displayed.
Now displays boxplots

ChartWindow now displays boxplots including sets with independent
(grouping) variables. All code seems to work but testing needed.