EclCpGridManager: disable parallelism (for now)

this is because the loadBalance() method of Dune::CpGrid is seriously
broken at the moment: it throws away elements even in sequential mode
for some more relevant grids. ("more relevant" == "Norne". Norne is is
buggy itself because it features two completely disjoint parts.)

but it is even worse than that: if the bug mentioned above bites,
Dune::CpGrid cannot even agree for itself how many elements it has
which causes the CartesianIndexMapper to segfault.

applications/ebos/eclcpgridmanager.hh

@@ -125,9 +125,15 @@ public:
      */
     void loadBalance()
     {
+#if HAVE_MPI
+#warning "Since Dune::CpGrid is buggy when load balancing, ebos currently disables parallelism"
+#endif
+#if 0
         // distribute the grid and switch to the distributed view
         grid_->loadBalance();
         grid_->switchToDistributedView();
+#endif
+
         cartesianIndexMapper_ = new CartesianIndexMapper(*grid_);
     }