Fix Child Container PhaseSpaceMulti

- child in PhaseSpaceMulti should be stored as pointers
  to avoid a second constructor call causing a chaning pointer
  and double-construct
- libSplash will support the ParallelDataConnector::finalize()
  call to free the internal dublicated MPI_Communicator again
  in 1.2+
- clean up some &/-> calls to avoid miss-understandings (no bug)
- update some copyright years
- parallel file name appends timestep itself