------------------
Breaking changes:
- Deprecate ``renderMessage(message)``,
use stdlibs ``message.as_string()`` from ``email.message.Message`` class instead.
[jensens]
- Newline handling in MIME-headers: ``\n`` are now escaped explicit.
This follows RFC2822 section 3.2.2.
[jensens]
- Drop support of Python 2.6
[jensens]
New features:
- ``constructMessage`` now handles base64 encoding automatically for all marshallers,
where ``marshaler.ascii`` is ``False`` and ``marshaler.getContentType`` is ``None``.
[jensens]
- Support for Python 3+
Also big code overhaul included.
[jensens]