configuration - allow PID file to be optional
✅ default PID location is in ${localstatedir}/run/knot/knot.pid
and could be changed with ./configure --with-rundir=$dir
✅ default storage location is in ${sharedstatedir}/knot
and could be changed with ./configure --with-storage=$dir
or storage in configuration
✅ rundir option in configuration, replacing pidfile
✅ knotd wouldn't be responsible for rundir to be created, just the file
✅ knotc start would be no more
✅ knotc stop|restart use the same channel as rest of the commands
✅ running knotd directly would NOT create a PID file (since we're in foreground)
✅ knotd -d would create it (since it runs daemonized, for compatibility with older init systems)
✅ AF_UNIX
sockets for knotc