Handing over cluttermm

I have not worked on the Clutter C++ API (cluttermm) much for the last few months, having no real need for it personally. But Chris Kühl is more enthusiastic.

I’m always looking for ways to give away responsibilities, so he is now the new cluttermm maintainer. He has already fixed several serious bugs, wrapped lots of new API, and put that all in new releases of 1.1 and 1.3. Please show him your thanks by trying it out and giving him some feedback.