comms/aprsd: cleanup & modernization

[feld]

Summary

I stumbled upon aprsd when grepping the ports tree and found it
violating several modern ports conventions. Here's a cleanup attempt.

[feld]

comms/aprsd/files/aprsd.in

55

actually this should be an "install /dev/null ..." like above because the pidfile might not yet exist if it has never been started before.

[feld]

Standardize actions in rc script start_precmd