Drop support for Python 2.4 / 2.5.
Added Python 3 support and a little test that at least tries to import 
all the interfaces to make sure the syntax works in all Python versions.
Preparing release 4.0.0
Back to development: 4.0.1
Sigh, forgot to add tox.ini to manifest.
Note the change.
Preparing release 4.0.1
Back to development: 4.0.2
Add a few more files, but will nto do another release. We can survive 
without them. If the builders scream, I will do another release.