Configure Leaflet.js with enhanced Layer control

[Curt-Whitmire-NOAA]

Because we've grouped many map layers into group folders, clicking a point on the map returns only one (top level?) layer's attributes. Investigate and integrate Leaflet layer groups and layer control to result in attributes of only checked layers. The goal is to create a similar user experience as is available in ArcGIS applications where when a map is clicked, a dialog box pops up with the option to arrow through multiple layers.