Map: Add overlay option for range rings

[kklemens]

Feature Request: Add an option in CeruleanMap to have range rings in 50m intervals coming from the plotted topside position. This will aid in understanding at what distance sync dropouts may be occurring so users know not to exceed the maximum range for the given conditions.

Also aids in understanding how far away a vehicle is from its support vessel/area for tether management reasons.

Recommend making it the same color green as the topside location indication.

[dennysb]

Thanks for the suggestion. We have added this to the CeruleanMap update list.