str2time("2008-10-29",   "GMT")   # --> Wed, 29 Oct 2008 00:00:00 GMT
str2time("2008-10-29", "-0800")   # --> Wed, 29 Oct 2008 08:00:00 GMT
str2time("2008-10-29", "+0100")   # --> Tue, 28 Oct 2008 23:00:00 GMT