o Also, use tagged release of ZODB-based externals.

Base the default location of softwarehome on Zope2, which is guaranteed not to be a namespace but always located inside the Zope2 software home. This fixes Zope2 breaking on systems which uses namespace packages for Products.*

Revert c81408 HelpSys changes, it didn't make much of a difference. Making the whole help system optional would be a better approach.

Revert ISO8601 interpretation to previously broken behaviour (assume GMT rather than local time as per spec)

(culprit from the last refactoring)

* Add support to timezone aware datetime conversion
* Correct capitalization of Brazil/DeNoronha

All previous timezone names are tested against the new pytz based timezones.
This test shows that the following zones changed when pytz support was added
(i.e. not in this commit):

t1 = time.mktime(datetime(2002, 1, 1).timetuple())
t2 = time.mktime(datetime(2002, 7, 1).timetuple())
expected_failures = [ # zone.info(t1)     newzone.info(t1)     zone.info(t2)     newzone.info(t2)
    'Jamaica',        # (-18000, 0, 'EST') (-18000, 0, 'EST') (-14400, 1, 'EDT') (-18000, 0, 'EST')
    'Turkey',         # (10800, 0, 'EET') (7200, 0, 'EET') (14400, 1, 'EET DST') (10800, 1, 'EEST')
    'Mexico/BajaSur', # (-25200, 0, 'MST') (-25200, 0, 'MST') (-25200, 0, 'MST') (-21600, 1, 'MDT')
    'Mexico/General', # (-21600, 0, 'CST') (-21600, 0, 'CST') (-21600, 0, 'CST') (-18000, 1, 'CDT')
    'Canada/Yukon',   # (-32400, 0, 'YST') (-28800, 0, 'PST') (-28800, 1, 'YDT') (-25200, 1, 'PDT')
    'Brazil/West',    # (-10800, 1, 'WDT') (-14400, 0, 'AMT') (-14400, 0, 'WST') (-14400, 0, 'AMT')
    'Brazil/Acre',    # (-14400, 1, 'ADT') (-18000, 0, 'ACT') (-18000, 0, 'AST') (-18000, 0, 'ACT')
    ]

The most likely explanation for this is that the old database was out of date.

Turned deprecation warnings for manage_afterAdd, manage_beforeDelete and manage_afterClone methods into discouraged warnings.

      - Launchpad #151020: HTTP_CHAR_SET headers containing 'x-user-defined'
        caused a LookupError exception. Unknown encodings are from now on
        silently discarded.

Launchpad #143902: Fixed App.ImageFile to use a stream iterator to output the file. Avoid loading the file content when guessing the mimetype and only load the first 1024 bytes of the file when it cannot be guessed from the filename.

Changed PageTemplateFile not to load the file contents on Zope startup anymore but on first access instead. This brings them inline with the zope.pagetemplate version and speeds up Zope startup.

will be present. Changes as per Andreas's request.

If no time zone information is given with a time, the time zone is assumed to be in some conventional local time zone.

that is a datetime.datetime instance. Timezone naive DateTimes may
be converted back to timezone naive datetime.datetime objects with
asdatetime(). All DateTime instances may be converted to a timezone
naive datetime.datetime in UTC with utcdatetime().

Now DateTime will use pytz for timezone data. The main advantage of this 
is that pytz has up to date daylight savings data.

Added LAZY_FILE_LOADING constant to PageTemplateFile. When set to True Page Template files aren't lo
aded and parsed on Zope startup anymore, but on first access instead. When complex add-ons like Plon
e are installed this can safe up to 30% of the Zope startup time. This gets a ZConfig switch ones I 
figured out how to write one ;)

possible to mix ZTC and non-ZTC tests much more freely.

data is used in preference of DateTime's data. However, all time zones 
that DateTime defines are still supported.

Launchpad #147201: treat container-class in zope.conf as a string, making it possible to use types from extra products directories.