[FEATURE] Add scale to new Geocaching map

[+tamruns]

The new Geocaching map would be enhanced by adding a scale. There is no obvious way to check the distance between two points on the map. This makes planning trips far more difficult.

 

The new Geocaching map with data from Leaflet gives much better detail (for Australia) with 10m contour interval but the lack of a scale undoes that benefit. Switching to the Google Road Maps produces a scale in the bottom right corner, but no contour lines. Using the terrain layer on the old map switches to a less useful 20m contour interval that vanishes if you zoom in too far.