by Patsy Franklin (2015-01-30):
- 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.