Provide helpers for Pymesh network dismantling

[pgaufillet]

It would be helpful to have short range detector for finding the LoPy4 on the field, especially when the operator dismantling is not the one who have deployed.

As the LoPy4 has to be in short range around the SportIdent station, a simple RSSI based approach using Bluetooth or WiFi + technique similar to search of avalanche victims should be usable.

As Bluetooth / WiFi are power consuming, it should be possible to enable/disable it based on a command through Pymesh from a border router, on an event (like loss of Pymesh connectivity) or at a given time (e.g. after the scheduled end of the event).

The detector can be a smartphone.