Doxygen documentation for mce-dev

[IMbackK]

https://github.com/maemo-leste/mce-dev provided some doxygen documentation for the mce dbus methods/signals
Since https://github.com/maemo-leste/mce is now absorbing mce-dev it should include those too but currently dose not

[MerlijnWajer]

This has code to mostly create doxygen doc strings from existing html doxygen, I think: https://github.com/spinal84/clockd/tree/docs-wip/contrib