Hover legend and interactive legend

Added examples of both a hoverLegend and interactiveLegend. The interactiveLegend could possibly replace both toggleLegend and hoverLegend, but at the moment, it feels a bit clunky, since all I did was copy code over to that class. 
jsdoc insufficiently descriptive - it is the same for both callback functions, probably someone looking at the jsdoc wants to know what the difference between the two is