Allow 24:00 at the end of version-2-format time zone files.

* zic.c (stringoffset): Allow 24:00.  POSIX.1-2008 allows 24:00,
even though older versions of POSIX maxed out at 23:59:59.
Patch from Arthur David Olson.
* tz-link.htm: Add pointer to tz.js.  Update URLs.
Incorporate data from Milne (1899).

The source is: Milne J. Civil time. Geogr J. 1899 Feb;13(2):173-94
<http://www.jstor.org/stable/1774359>.
* africa (Africa/Gaborone, Africa/Cairo):
* asia (Asia/Rangoon, Asia/Shanghai, Asia/Hong_Kong, Asia/Aden):
* australasia (Pacific/Fiji):
* europe (Europe/Vienna):
* northamerica (America/Nassau, America/Barbados, Atlantic/Bermuda)
(America/Costa_Rica):
* southamerica (America/Bogota, America/Curacao):
Adjust old time stamps to match Milne.  I went going through
Milne's list one by one and did not finish, but the rest can be
done later.
Chile is changing its DST rules.

Thanks to Steffen Thorsen for the heads-up, in
<http://mm.icann.org/pipermail/tz/2013-February/018623.html>.
* antarctica (ChileAQ):
* southamerica (Chile):
Assume the 2012 rules will continue indefinitely.  Suggested by Robert
Elz in <http://mm.icann.org/pipermail/tz/2013-February/018636.html>.