ENH: Do a weighted balance before refinement and layer addition.

Have weight=7 on cells to be refined and balance. Then after refinement
there will be perfect balancing. Similar for layer addition.

src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.H

@@ -656,6 +656,16 @@ public:
                 const scalar maxLoadUnbalance
             );
 
+            //- Balance before refining some cells
+            autoPtr<mapDistributePolyMesh> balanceAndRefine
+            (
+                const string& msg,
+                decompositionMethod& decomposer,
+                fvMeshDistribute& distributor,
+                const labelList& cellsToRefine,
+                const scalar maxLoadUnbalance
+            );
+
 
         // Baffle handling