Python 3 support

[Stefan Fuhrmann <st...@apache.org>]

Hi all,

Under Linux, /trunk has now support for running our test suite
with Python 3. I tested various parameter combinations, ra layers
as well as backends and I call it quits.

On Windows, Python 3 will not work b/c win-tests.py has not been
adapted. Furthermore, there are fundamental issues with the EOL
handling that may be require significant work. Any other platform
that does not use '\n' natively may be affected as well.

Scripts outside /build and /subversion/tests have been partially
adapted (as part of global search and replace) but not received
any testing. We might either keep, improve or revert them.

-- Stefan^2.