Traditionally IANA has distributed their timezone data in pure source
form, replete with extensive historical comments.  As of release 2017c,
they've added a compact single-file format that omits comments and
abbreviates command keywords.  This form is way shorter than the pure
source, even before considering its allegedly better compressibility.
Hence, let's distribute the data in that form rather than pure source.

I'm pushing this now, rather than at the next timezone database update,
so that it's easy to confirm that this data file produces compiled zic
output that's identical to what we were getting before.

Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us

DST law changes in Fiji, Namibia, Northern Cyprus, Sudan, Tonga,
and Turks & Caicos Islands.  Historical corrections for Alaska, Apia,
Burma, Calcutta, Detroit, Ireland, Namibia, and Pago Pago.

DST law changes in Chile, Haiti, and Mongolia.  Historical corrections for
Ecuador, Kazakhstan, Liberia, and Spain.

The IANA crew continue their campaign to replace invented time zone
abbrevations with numeric GMT offsets.  This update changes numerous zones
in South America, the Pacific and Indian oceans, and some Asian and Middle
Eastern zones.  I kept these abbreviations in the tznames/ data files,
however, so that we will still accept them for input.  (We may want to
start trimming those files someday, but I think we should wait for the
upstream dust to settle before deciding what to do.)

In passing, add MESZ (Mitteleuropaeische Sommerzeit) to the tznames lists;
since we accept MEZ (Mitteleuropaeische Zeit) it seems rather strange not
to take the other one.  And fix some incorrect, or at least obsolete,
comments that certain abbreviations are not traceable to the IANA data.

DST law changes in Turkey.  Historical corrections for America/Los_Angeles,
Europe/Kirov, Europe/Moscow, Europe/Samara, and Europe/Ulyanovsk.
Rename Asia/Rangoon to Asia/Yangon, with a backward compatibility link.

The IANA crew continue their campaign to replace invented time zone
abbrevations with numeric GMT offsets.  This update changes numerous zones
in Antarctica and the former Soviet Union, for instance Antarctica/Casey
now reports "+08" not "AWST" in the pg_timezone_names view.  I kept these
abbreviations in the tznames/ data files, however, so that we will still
accept them for input.  (We may want to start trimming those files someday,
but today is not that day.)

An exception is that since IANA no longer claims that "AMT" is in use
in Armenia for GMT+4, I replaced it in the Default file with GMT-4,
corresponding to Amazon Time which is in use in South America.  It may be
that that meaning is also invented and IANA will drop it in a future
update; but for now, it seems silly to give pride of place to a meaning
not traceable to IANA over one that is.

DST law changes in Cayman Islands, Metlakatla, Trans-Baikal Territory
(Zabaykalsky Krai).  Historical corrections for Pakistan.

DST law changes in Egypt, Mongolia, Palestine.
Historical corrections for Canada and Chile.
Revised zone abbreviation for America/Adak (HST/HDT not HAST/HADT).

DST law changes in Chile and Mexico (state of Quintana Roo).
Historical changes for Iceland.

Most zones in the Russian Federation are subtracting one or two hours
as of 2014-10-26.  Update the meanings of the abbreviations IRKT, KRAT,
MAGT, MSK, NOVT, OMST, SAKT, VLAT, YAKT, YEKT to match.

The IANA timezone database has adopted abbreviations of the form AxST/AxDT
for all Australian time zones, reflecting what they believe to be current
majority practice Down Under.  These names do not conflict with usage
elsewhere (other than ACST for Acre Summer Time, which has been in disuse
since 1994).  Accordingly, adopt these names into our "Default" timezone
abbreviation set.  The "Australia" abbreviation set now contains only
CST,EAST,EST,SAST,SAT,WST, all of which are thought to be mostly historical
usage.  Note that SAST has also been changed to be South Africa Standard
Time in the "Default" abbreviation set.

Add zone abbreviations SRET (Asia/Srednekolymsk) and XJT (Asia/Urumqi),
and use WSST/WSDT for western Samoa.

Also a DST law change in the Turks & Caicos Islands (America/Grand_Turk),
and numerous corrections for historical time zone data.

DST law changes in Argentina, Brazil, Jordan, Libya, Liechtenstein,
Morocco, Palestine.  New timezone abbreviations WIB, WIT, WITA for
Indonesia.

DST law changes in Morocco; Tokelau has relocated to the other side of
the International Date Line; and apparently Olson had Tokelau's GMT
offset wrong by an hour even before that.

There are also a large number of non-significant changes in this update.
Upstream took the opportunity to remove trailing whitespace, and the
SCCS-style version numbers on the individual files are gone too.