Merge branch 'fix/deprecationwarnign-dune29' into 'master'

Remove deprecation warnings with dune 2.9

See merge request !133

exercises/exercise-mainfile/exercise1pamain.cc

@@ -137,7 +137,7 @@ int main(int argc, char** argv)
 
     timer.stop();
 
-    const auto& comm = Dune::MPIHelper::getCollectiveCommunication();
+    const auto& comm = leafGridView.comm();
     std::cout << "Simulation took " << timer.elapsed() << " seconds on "
               << comm.size() << " processes.\n"
               << "The cumulative CPU time was " << timer.elapsed()*comm.size() << " seconds.\n";

exercises/exercise-mainfile/exercise1pbmain.cc

@@ -127,7 +127,7 @@ int main(int argc, char** argv)
 
     timer.stop();
 
-    const auto& comm = Dune::MPIHelper::getCollectiveCommunication();
+    const auto& comm = leafGridView.comm();
     std::cout << "Simulation took " << timer.elapsed() << " seconds on "
               << comm.size() << " processes.\n"
               << "The cumulative CPU time was " << timer.elapsed()*comm.size() << " seconds.\n";

exercises/solution/exercise-mainfile/exercise1pa_solution_main.cc

@@ -139,7 +139,7 @@ int main(int argc, char** argv)
 
     timer.stop();
 
-    const auto& comm = Dune::MPIHelper::getCollectiveCommunication();
+    const auto& comm = leafGridView.comm();
     std::cout << "Simulation took " << timer.elapsed() << " seconds on "
               << comm.size() << " processes.\n"
               << "The cumulative CPU time was " << timer.elapsed()*comm.size() << " seconds.\n";