Start 2.2.0

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
Coverage removal

* Coverage is not really supported for Cython modules.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
intbitset automatic documentation

* Automatically generates intbitset documentation
  by using Sphinx automodule functionality.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>