python: Build for both Python2 and Python3.
* NEWS: Update. * configure.ac: Check for multiple Python versions. * lang/python/Makefile.am: Build and install for both Python versions. * lang/python/tests/Makefile.am: Test both versions. * lang/python/tests/run-tests.py: New test runner.
- Signed-off-by: Justus Winter <justus@g10code.com>