Don't save config while we're reading it from disk.
Change the way we handle the daemon: if we can't communicate with it
for 1 second (which is possible), start a new one. The daemon saves
its pid in daemonpid; on each iteration of the main loop the daemon
checks whether it's still in favour. If not, it silently exits.
Also, when trying to communicate with the daemon, check daemonpid
first. If it's set to 0, don't even try.
time out on an operation. Under these circumstances, vinum(8) will
automatically start another daemon. Add a pid for the daemon, so that
an overtaken daemon will discover that it's no longer in favour, and
will crawl into a corner and die.
