Rebase to 2015a
- New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.
- The Mexican state of Quintana Roo, represented by America/Cancun,
will shift from Central Time with DST to Eastern Time without DST
on 2015-02-01 at 02:00.
- Chile will not change clocks in April or thereafter; its new standard time
will be its old daylight saving time. This affects America/Santiago,
Pacific/Easter, and Antarctica/Palmer.