change printf() calls to log() calls.

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.