functions: implement support for readahead restore
tuned: restart ktune 10 seconds after last SIGUSR2 was received

When multiple devices are added into the system, udev restarted ktune
daemon for each new device. This can cause races within ktune. This
mechanism allows triggering just one ktune restart when multiple
devices are inserted.
udev rules: ask tuned to restart ktune instead of restarting it directly
new release (0.2.23)