ENH: snappyHexMesh: multi-stage layer addition, automatic hole closure

Automatic hole closure:
- introduces 'holeToFace' topoSet source
- used when detecting a 'leak-path'
- creates additional baffles to close the leak

Multi-stage layer addition:
- Can add layers in multiple passes

See issues: #2403, #2404

tutorials/mesh/snappyHexMesh/addLayersToFaceZone/system/decomposeParDict

@@ -14,25 +14,9 @@ FoamFile
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-numberOfSubdomains  2;
-
-//- Use the volScalarField named here as a weight for each cell in the
-//  decomposition.  For example, use a particle population field to decompose
-//  for a balanced number of particles in a lagrangian simulation.
-// weightField dsmcRhoNMean;
-
-method          scotch;
-
-constraints
-{
-    //- Keep owner and neighbour of baffles on same processor
-    //  (i.e. keep it detectable as a baffle).
-    //  Baffles are two boundary face sharing the same points.
-    baffles
-    {
-        type    preserveBaffles;
-    }
-}
+numberOfSubdomains  3;
 
+// For testing only: use random decomposition.
+method              random;
 
 // ************************************************************************* //