Handle selections with CSS, rather than a separate FeatureGroup.

[Philip Griffith]

This is likely lighter as it simply involves CSS styling through HTML attributes, rather than a Leaflet FeatureGroup for a single marker.

[Clinton Lunn]

I am doing some reading on this so I will paste some resources that I have found. We may be able to reorder the map panes in order to show/hide display of certain points.

leaflet map panes documentation
[leaflet css point ordering issue (old, but gets at the use of panes in decent detail](Leaflet/Leaflet#1734
[scroll to bottom to turn off markers based on id] (Leaflet/Leaflet#4)

[Philip Griffith]

I think this is no longer a relevant issue.