[tz] attic data for the tz database

[Zefram]

Paul Eggert wrote:
>Yes, I'd thought about that.  Maintaining the population figures would
>be a bit of a pain (and another source of arguments!),

It doesn't require much maintenance.  We don't really need to update them,
because the relative population figures only change slowly.  It should
suffice to collect a single figure per location, the estimated population
for a common reference date.  I suggest a nominal reference date of 2010
(-01-01T00:00:00Z, for the picky).  We can think about switching to a
new reference date in 2020.  (There's a thought here to the possible
future extension to sort on population as it was at the user's choice
of historical era, for which population figures at decadal intervals
should be adequate.)

As a test, I just picked five entries from tz2013d zone.tab at random,
and looked up the locations on Wikipedia.  (Indian/Maldives, Asia/Almaty,
Asia/Vientiane, America/Martinique, Atlantic/Reykjavik.)  In all five
cases the infobox at the top of the article gives a recent population
figure, with date, dates ranging from 2007-01-01 to 2013-02-01.  Three
out of five gave a citation specifically for the population figure.
Using those figures as-is should suffice for our purposes, or we can
crudely correct for the variable dates by applying an exponential model
of short-term population growth.

I'd be inclined to stick the population figures in the zone source files,
probably as a magic comment to avoid breaking anyone's zic.  An automated
process can generate a .tab from that.

-zefram