Fix charset of first text-part of outgoing multipart messages... ...thanks Dirk Geschke for reporting, see http://thread.gmane.org/gmane.comp.bug-tracking.roundup.user/10223 This also adds some regression tests to test incoming latin1 and outgoing single- and multipart utf-8 and latin1 messages

#!/usr/bin/env python
import zlib, base64, sys
print base64.encodestring(zlib.compress(sys.stdin.read()))