message: In class GroupTopology, make some methods const.
diff: @@ -78,9 +78,9 @@ public:
  GroupTopology(const GroupTopology &gt);
  void SetComm(MPI_Comm comm) { MyComm = comm; }
  - MPI_Comm GetComm() { return MyComm; }
  - int MyRank() { int r; MPI_Comm_rank(MyComm, &r); return r; }
  - int NRanks() { int s; MPI_Comm_size(MyComm, &s); return s; }
  + MPI_Comm GetComm() const { return MyComm; }
  + int MyRank() const { int r; MPI_Comm_rank(MyComm, &r); return r; }
  + int NRanks() const { int s; MPI_Comm_size(MyComm, &s); return s; }
  void Create(ListOfIntegerSets &groups, int mpitag);
  