ENH: complete reworking of foamToEnsight to make into a library (issue #241)

- eliminate ensightAsciiStream, ensightBinaryStream, ensightStream in
  favour of using ensightFile and ensightGeoFile classes throughout.

- encapsulate mesh-parts sorting with the ensightCells, ensightFaces
  class.

- handle of patches/faceZones entirely within ensightMesh for a lighter
  interaction with field output. Both faceZones and point fields need
  more testing to see if they behave properly for all cases.

- move some output functionality into its own namespace
  'ensightOutput', move into a library.

- use the ensightCase class to open new ensight output streams
  in the proper sub-directory locations.

applications/utilities/postProcessing/dataConversion/foamToEnsight/meshSubsetHelper.H

@@ -0,0 +1,193 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
+     \\/     M anipulation  | Copyright (C) 2016 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::meshSubsetHelper
+
+Description
+    Simple helper to hold a mesh or mesh-subset and provide uniform access.
+
+SourceFiles
+    meshSubsetHelper.C
+    meshSubsetHelperTemplates.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef meshSubsetHelper_H
+#define meshSubsetHelper_H
+
+#include "fvMeshSubset.H"
+#include "zeroGradientFvPatchField.H"
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward declaration of classes
+class Time;
+
+/*---------------------------------------------------------------------------*\
+                      Class meshSubsetHelper Declaration
+\*---------------------------------------------------------------------------*/
+
+class meshSubsetHelper
+{
+    // Private data
+
+        //- Reference to mesh
+        fvMesh& baseMesh_;
+
+        //- Subsetting engine + sub-fvMesh
+        fvMeshSubset subsetter_;
+
+        //- Name of current cellSet/cellZone (or empty)
+        const word name_;
+
+        //- Internal book-keeping. 0 = unused, 1 = set, 2 = zone
+        const int type_;
+
+
+    // Private Member Functions
+
+        //- Disallow default bitwise copy construct
+        meshSubsetHelper(const meshSubsetHelper&) = delete;
+
+        //- Disallow default bitwise assignment
+        void operator=(const meshSubsetHelper&) = delete;
+
+
+public:
+
+    // Constructors
+
+        //- Construct from components
+        meshSubsetHelper
+        (
+            fvMesh& baseMesh,
+            const word& name = word::null,
+            const bool isCellSet = false
+        );
+
+
+    // Member Functions
+
+    // Access
+
+        //- The entire base mesh
+        inline const fvMesh& baseMesh() const
+        {
+            return baseMesh_;
+        }
+
+        //- The mesh subsetter
+        inline const fvMeshSubset& subsetter() const
+        {
+            return subsetter_;
+        }
+
+        //- Check if running a sub-mesh is being used
+        inline bool useSubMesh() const
+        {
+            return type_;
+        }
+
+        //- Access either mesh or submesh
+        inline const fvMesh& mesh() const
+        {
+            if (useSubMesh())
+            {
+                return subsetter_.subMesh();
+            }
+            else
+            {
+                return baseMesh_;
+            }
+        }
+
+
+    // Edit
+
+        //- Update mesh subset
+        void correct(bool verbose = false);
+
+        //- Read mesh
+        polyMesh::readUpdateState readUpdate();
+
+
+        //- Construct volField (with zeroGradient) from an internal field
+        template<class Type>
+        static tmp<GeometricField<Type, fvPatchField, volMesh>>
+        zeroGradientField
+        (
+            const typename GeometricField
+            <
+                Type,
+                fvPatchField,
+                volMesh
+            >::Internal& df
+        );
+
+
+        //- Wrapper for field or the subsetted field.
+        //  Map volume field (does in fact do very little interpolation;
+        //  just copied from fvMeshSubset)
+        template<class Type>
+        tmp<GeometricField<Type, fvPatchField, volMesh>>
+        interpolate
+        (
+            const GeometricField<Type, fvPatchField, volMesh>&
+        ) const;
+
+
+        //- Convert an internal field to a volume field
+        template<class Type>
+        tmp<GeometricField<Type, fvPatchField, volMesh>>
+        interpolate
+        (
+            const typename GeometricField
+            <
+                Type,
+                fvPatchField,
+                volMesh
+            >::Internal&
+        ) const;
+
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "meshSubsetHelperTemplates.C"
+#endif
+
+
+#endif
+
+// ************************************************************************* //