message: ParaView bug: flush stream before calling tellp
  When compiling on Windows with MinGW, tellp does not return
  the updated file position unless flush is called first.
diff: @@ -988,6 +988,7 @@ void ParaViewDataCollection::Save()
  pvd_stream << "<DataSet timestep=\"" << GetTime(); // GetCycle();
  pvd_stream << "\" group=\"\" part=\"" << 0 << "\" file=\"";
  pvd_stream << fname << "\"/>\n";
  + pvd_stream.flush();
  std::fstream::pos_type pos = pvd_stream.tellp();
  pvd_stream << "</Collection>\n";
  pvd_stream << "</VTKFile>" << std::endl;
  