message: In navier_turbchan.cpp, switch to Mpi::Init() instead of
  MPI_Session similar to all other examples and miniapps.
diff: @@ -89,7 +89,8 @@ void vel_wall(const Vector &x, double t, Vector &u)
  int main(int argc, char *argv[])
  {
  - MPI_Session mpi(argc, argv);
  + Mpi::Init();
  + Hypre::Init();
  double Lx = 2.0 * M_PI;
  double Ly = 1.0;
  @@ -121,7 +122,7 @@ int main(int argc, char *argv[])
  Mesh periodic_mesh = Mesh::MakePeriodic(mesh,
  mesh.CreatePeriodicVertexMapping(translations));
  - if (mpi.Root())
  + if (Mpi::Root())
  {
  printf("NL=%d NX=%d NY=%d NZ=%d dx+=%f\n", NL, NX, NY, NZ, LC * ctx.Re_tau);
  std::cout << "Number of elements: " << mesh.GetNE() << std::endl;
  @@ -193,7 +194,7 @@ int main(int argc, char *argv[])
  dt = 1e-2;
  }
  - if (mpi.Root())
  + if (Mpi::Root())
  {
  printf("%11s %11s\n", "Time", "dt");
  printf("%.5E %.5E\n", t, dt);
  