Prevent shutdown ordering crashes

No need to add dynamic MockLink comm links

No signing support yet

_finalize methods need information which is not available if all you
have is a mavlink_message_t

Also change Plan Element selection ui

* Add support for another board

* Added a 2nd custom board

This mechanism automatically queues data into the correct thread where necessary, otherwise the method is invoked directly with low overhead.

At the same time remove the UDP socket event workaround. It is not a problem.

3DR Radios no longer exist

Plus other auto connect bug fixes

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

- Also fix vehicle selector dropdown in toolbar