*   Throughout the library, change from `UTCTime` to `ZonedTime`, except for
    situations where the official site uses actual UTCTime.  The main change is
    in `challengeReleaseTime`.
*   `challengeReleaseTime` moved to *Advent.Types* but re-exported from
    *Advent*.
*   `dlbmTime` changed from `UTCTime` to `NominalDiffTime` `dlbmDecTime`, which
    is time from December 1st.  This is because we don't have information about
    the year from the HTML returned alone.  This fixes a bug where the time
    would always be in 1970.
*   To convert `dlbmDecTime` back into a useful time,added `dlbmCompleteTime`
    to get the actual time of completion (as a `ZonedTime`), and `dlbmTime` to
    get the `NominalDiffTime` representing how long the challenge took.