For data import, figure out how to allow user to select gage and weather stations by clicking

[ellenmonster]

I think after the "Highlight selected sites" step, I can have code switch to marker click for the gage and weather stations instead of HUC level. But currently, clicking on those provides more information so I can't have clicking serve both purposes simultaneously. Need to think about this. Perhaps detailed hover info should show up in a separate box in the map, then I can use the click just for selection