Support multiple vehicles, multiple ground stations

[rmackay9]

Perhaps this has come up before but I think the current mavesp firmware only supports connecting with a single ground stations. It would be nice if multiple ground stations could be connected.

By the way, ardupilot also supports "drone follow" (one or more vehicles following a lead vehicle without the use of a ground stations). It would be nice if we could use mavesp to easily connect up the vehicles. I.e. the lead vehicle would create an access point, the following vehicles would connect to it using "station" mode. I think this basically works but the follow vehicles do not get the lead vehicle's position (at least in my testing).