Modernize DetDesc

* make reference counting in Services thread safe by use of
  shared_ptr / weak_ptr
* prefer static const data over member data if it is invariant
* prefer struct over class if all member data/functions are public
* do not explicitly implement destructor if the implicitly generated
  one is sufficient
* remove obsolete CVS/SVN keywords
* add final if possible
* remove commented out code
* prefer auto