Fixed

- Fixed NTP socket binding on dual-stack hosts so the socket address family matches the server being polled.
- Clarified the shared memory protocol (shm1): the oscillator period error is a unit-less relative error. The writer
  was updated to match.

Changed

- The `clockbound` daemon now writes `maxerror` and `esterror` (set to the clock error bound) when adjusting the system
  clock
- Further tuning of the clock synchronization algorithm