Python 3 support, established using 2to3
Python 3 support improved

Found missing bytes/string conversions in some places, fixed now
Python 3 support improved

Checksumming ported
Use STARTTLS by default and warn if using unencrypted connection
Support Python 2, which does not support STARTTLS
Some more fixes to make devurandom's Python 3 stuff work on Python 2
Merge branch 'devurandom' and fix conflicts