collectivecomm is deprecated use communication instead

CollecticeCommunication is now deprecated in dune-common and Communication to be used. This merge request simply replace all CCon with Com which means CollectiveCommunicationType typedefs in classes are also changed without deprecation. Should we

1. just go ahead with this without deprecation assuming that CComm is not really used that much outside of dune-fem
2. deprecate CCommType in all dune-fem classes and do this slowly
3. only change Dune::CollectiveComm but keep the dune-fem type

Should wait: in the grid it is still CollectiveCommunication and it is not clear to me how this will be resolved.