- The release version is only stored in two places now: The file
  picos/.version and the annotatd git tag. Both can be validated, read
  and bumped with the new version.py script.
- Conda builds use the same version as setuptools (both generated from
  version.py; including the number of extra commits as fourth digit).
- MANIFEST and MANIFEST.in are removed as they seem to serve no purpose.
- LICENSE.txt was stripped of an unnecessary trailer.
- unitTest/doctest_py3.py is now at test_picos2.py and will later be
  superseded by test.py (which does not exist on this commit).
- .gitignore was reworked.