Maildirproc

- Tweaks to packaging, no functional changes.

- Added env_sender parameter to forward and forward_copy methods.

- maildirproc is now a Python 3.x project. Install maildirproc-python2 for
Python 2.x compatibility.

- Logs are now printed to the log file in a safe way even if the log string
doesn't fit within the destination character set.

- Improved robustness for erroneously encoded headers when running Python
3.x.
- Fixed problem with logging to stdout when running Python 3.x.

- Improved robustness for erroneously encoded headers.
- Made it possible to log non-ASCII characters from the RC file.