Sync zoneinfo database with tzdata2013a from ftp://ftp.iana.org/tz/releases

* antarctica & southamerica: Chile's 2013 rules, and we guess rules for
    2014 and later, will be the same as 2012, namely Apr Sun>=23 03:00 UTC
    to Sep Sun>=2 04:00 UTC. (Thanks to Steffen Thorsen and Robert Elz.)

* europe: New "Asia/Khandyga" and "Asia/Ust-Nera" and "Europe/Busingen"
    zones. Also, improve the commentary about which districts observe
    what times in Russia. (Thanks to Tobias Conradi, Oscar van Vlijmen
    and Arthur David Olson.)

* various files: Many changes affecting historical time stamps before
    1940. These were deduced from: Milne J. Civil time. Geogr J. 1899
    Feb;13(2):173-94 <http://www.jstor.org/stable/1774359>.
bce: Strip extra blank lines