flow_ebos: only instantiate the grid once

it now uses the grid object which gets created by ebos for everything
which should make the parallelization efforts easier. I also tried to
cut back the use of the legacy property objects (i.e., for the fluid,
geologic and rock properties), but this effort ran aground because of
the initialization and output code. (also, if those two were fixed,
there would probably be issues with the Newton update.)

I ran Norne with this and there did not seem to be any notable
performance regressions or benefits.

opm/autodiff/GridInit.hpp

@@ -73,18 +73,42 @@ namespace Opm
     class GridInit<Dune::CpGrid>
     {
     public:
+        GridInit()
+        {
+            gridSelfManaged_ = false;
+        }
+
         /// Initialize from a deck and/or an eclipse state and (logical cartesian) specified pore volumes.
         GridInit(const EclipseState& eclipse_state, const std::vector<double>& porv)
         {
-            grid_.processEclipseFormat(eclipse_state.getInputGrid(), false, false, false, porv);
+            gridSelfManaged_ = true;
+
+            grid_ = new Dune::CpGrid;
+            grid_->processEclipseFormat(eclipse_state.getInputGrid(), false, false, false, porv);
         }
+
+        ~GridInit()
+        {
+            if (gridSelfManaged_)
+                delete grid_;
+        }
+
         /// Access the created grid. Note that mutable access may be required for load balancing.
         Dune::CpGrid& grid()
         {
-            return grid_;
+            return *grid_;
         }
+
+        /// set the grid from the outside
+        void setGrid(Dune::CpGrid& newGrid)
+        {
+            gridSelfManaged_ = false;
+            grid_ = &newGrid;
+        }
+
     private:
-        Dune::CpGrid grid_;
+        Dune::CpGrid* grid_;
+        bool gridSelfManaged_;
     };
 #endif // HAVE_OPM_GRID