ENH: snappyHexMesh: express small regions. Fixes #2379

Extend selection of small cells to use absolute cell count

src/mesh/snappyHexMesh/snappyHexMeshDriver/refinementParameters/refinementParameters.C

@@ -95,6 +95,7 @@ Foam::refinementParameters::refinementParameters
     nErodeCellZone_(dict.getOrDefault<label>("nCellZoneErodeIter", 0)),
     nFilterIter_(dict.getOrDefault<label>("nFilterIter", 2)),
     minCellFraction_(dict.getOrDefault<scalar>("minCellFraction", 0)),
+    nMinCells_(dict.getOrDefault<label>("nMinCells", 0)),
     dryRun_(dryRun)
 {
     point locationInMesh;