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- Drop support for Python 2.6 and 3.2.
- Add support for Python 3.5 and 3.6.
- Fix the ``domain`` of MessageID fields to be a native string.
Previously on Python 3 they were bytes, which meant that they
couldn't be used to find translation utilities registered by
zope.i18n. See `issue 17 <https://github.com/zopefoundation/zope.configuration/issues/17>`_.