Seconds in str(DateTime()) are not zero-padded

[Artur Zaprzała]

__str__() method of DateTime is using '%06.6f' format for seconds, which clearly is not what the author intended. It should be '%09.6f'.
A bad thing is that everyone is using diffrent format string for the same result. For example, the following formats are equivalent: '%02d', '%02.2d', '%2.2d', '%.2d'.

By the way I found a bug in _tzoffset2rfc822zone() and _tzoffset2iso8601zone(). Someone overlooked that in Python division is a floor division. As a result, a timezone '-0230' will be formatted as '-0330'.

The attached patch will do the following:
 - fix __str__ method,
 - make all format strings consistent,
 - fix _tzoffset2rfc822zone() and _tzoffset2iso8601zone() functions,
 - change _findLocalTimeZoneName() to use _tzoffset2rfc822zone() instead of a very complicated code.

[Tres Seaver (tseaver)]

This patch looks reasonable. Needs tests.

[Colin Watson (cjwatson)]

The datetime project on Launchpad has been archived at the request of the Zope developers (see https://answers.launchpad.net/launchpad/+question/683589 and https://answers.launchpad.net/launchpad/+question/685285). If this bug is still relevant, please refile it at https://github.com/zopefoundation/datetime.