STYLE: revert bitSet/HashSet setMany() to set() method (issue #837)

- improves backward compatibility and more naming consistency.
  Retain setMany(iter1, iter2) to avoid ambiguity with the
  PackedList::set(index, value) method.

applications/utilities/mesh/manipulation/polyDualMesh/meshDualiser.C

@@ -891,7 +891,7 @@ void Foam::meshDualiser::setRefinement
     {
         const labelList& fEdges = mesh_.faceEdges()[facei];
 
-        isBoundaryEdge.setMany(fEdges);
+        isBoundaryEdge.set(fEdges);
     }