Update .gitignore:

* ignore /tests/... (was still /buildtests/...)
* ignore /dist/, too
* ignore directories, where directories are meant
* changes /e2etests to /old/e2etests (was moved there)
Update MANIFEST.in:

* remove .hgignore (was removed long ago)
* exclude all .pyc and .pyo files
Add a Readme-file for tests for how-to run tests.