Add selectionable layers into 'general' map

[alexcorvis84]

It would be great to add an option to show different layers on the 'general' map based on leaflet library, where stations & satellites are showed.

Reason: sometimes you just want to know where are ONLY located the satellites, and they are hide due the large number of stations shown. Including different layers selection could be a nice feature (satellites, stations or adding more type of layers)