ENH: improvements for makeFaMesh, checkFaMesh

- added -dry-run, -write-vtk options.
  Additional mesh information after creation.

- add parallel reductions and more information for checkFaMesh

ENH: minor cleanup of faPatch internals

- align pointLabels and pointEdges creation more closely with coding
  patterns used in PrimitivePatch

- use fileHandler when loading "S0" field.

applications/utilities/finiteArea/checkFaMesh/printMeshSummary.H

@@ -0,0 +1,134 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2021 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
+
+Description
+    Summary of faMesh information
+
+\*---------------------------------------------------------------------------*/
+
+{
+    const faBoundaryMesh& patches = aMesh.boundary();
+    const label nNonProcessor = patches.nNonProcessor();
+    const label nPatches = patches.size();
+
+    Info<< "----------------" << nl
+        << "Mesh Information" << nl
+        << "----------------" << nl
+        << "  " << "boundingBox: " << boundBox(aMesh.points()) << nl;
+
+    Info<< "  Number of points: "
+        << returnReduce(aMesh.nPoints(), sumOp<label>()) << nl
+        << "  Number of faces: "
+        << returnReduce(aMesh.nFaces(), sumOp<label>()) << nl;
+
+    Info<< "  Number of edges: "
+        << returnReduce(aMesh.nEdges(), sumOp<label>()) << nl
+        << "  Number of internal edges: "
+        << returnReduce(aMesh.nInternalEdges(), sumOp<label>()) << nl;
+
+
+    label nProcEdges = 0;
+
+    if (Pstream::parRun())
+    {
+        for (const faPatch& fap : patches)
+        {
+            const auto* cpp = isA<processorFaPatch>(fap);
+
+            if (cpp)
+            {
+                nProcEdges += fap.nEdges();
+            }
+        }
+    }
+
+    const label nBoundEdges = aMesh.nBoundaryEdges() - nProcEdges;
+
+    Info<< "  Number of boundary edges: "
+        << returnReduce(nBoundEdges - nProcEdges, sumOp<label>()) << nl;
+
+    if (Pstream::parRun())
+    {
+        Info<< "  Number of processor edges: "
+            << returnReduce(nProcEdges, sumOp<label>()) << nl;
+    }
+
+
+    Info<< "----------------" << nl
+        << "Patches" << nl
+        << "----------------" << nl;
+
+    for (label patchi = 0; patchi < nNonProcessor; ++patchi)
+    {
+        const faPatch& p = patches[patchi];
+
+         Info<< "  " << "patch " << p.index()
+             << " (size: " << returnReduce(p.size(), sumOp<label>())
+             << ") name: " << p.name()
+             << nl;
+    }
+
+
+    // Geometry information
+    Info<< nl;
+    {
+        scalarMinMax limit(gMinMax(aMesh.S().field()));
+        Info<< "Face area:" << nl
+            << "    min = " << limit.min() << " max = "  << limit.max() << nl;
+    }
+
+    {
+        scalarMinMax limit(minMax(aMesh.magLe().primitiveField()));
+
+        // Include processor boundaries into 'internal' edges
+        if (Pstream::parRun())
+        {
+            for (label patchi = nNonProcessor; patchi < nPatches; ++patchi)
+            {
+                limit.add(minMax(aMesh.magLe().boundaryField()[patchi]));
+            }
+
+            reduce(limit, minMaxOp<scalar>());
+        }
+
+        Info<< "Edge length (internal):" << nl
+            << "    min = " << limit.min() << " max = "  << limit.max() << nl;
+
+
+        // Include (non-processor) boundaries
+        for (label patchi = 0; patchi < nNonProcessor; ++patchi)
+        {
+            limit.add(minMax(aMesh.magLe().boundaryField()[patchi]));
+        }
+
+        if (Pstream::parRun())
+        {
+            reduce(limit, minMaxOp<scalar>());
+        }
+
+        Info<< "Edge length:" << nl
+            << "    min = " << limit.min() << " max = "  << limit.max() << nl;
+    }
+
+    // Not particularly meaningful
+    #if 0
+    {
+        MinMax<vector> limit(gMinMax(aMesh.faceAreaNormals().field()));
+
+        Info<< "Face area normals:" << nl
+            << "    min = " << limit.min() << " max = " << limit.max() << nl;
+    }
+    #endif
+}
+
+
+// ************************************************************************* //