No signing support yet

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

This reverts commit ae976049ca7b4818616e6b8be07a028fc7dfc26f.

Also change Plan Element selection ui

* Add support for another board

* Added a 2nd custom board

- Now responds to request_list using a worker routine to send out
params one at a time
- Support for failure modes for unit testing

- Delay gps position for better testing
- Longer delay on home position

Obligate LinkInterfaces to implement getLinkConfiguration. 11ab9aa0 introduced a bug where TCP links would cause a crash loading the sensors page