[Cython] release preparations for 0.22.1 and 0.23

[Stefan Behnel]

Hi,

I think it's about time for a new release. I propose to relase 0.22.1 in
the next days, and then start the release cycle for 0.23.

Please make sure everything that you consider a safe bug fix is in the
0.22.x branch. I already copied Jeroen's latest fixes over.

Stefan