ENH: new PDRblockMesh mesh generation utility (issue #1216)

- While a rectilinear mesh can be created with blockMesh, not every mesh
  created with blockMesh will satisfy the requirements for being a
  rectilinear mesh.

  This alternative to blockMesh uses a single block that is aligned
  with the xy-z directions and specifications of the control points,
  mesh divisions and expansion ratios. For example,

    x
    {
        points  ( -13.28 -0.10 6.0 19.19 );
        nCells  (  10  12 10 );
        ratios  ( 0.2   1  5 );
    }

    y { ... }
    z { ... }

  With only one block, the boundary patch definition is simple and the
  canonical face number is used directly. For example,

    inlet
    {
        type    patch;
        faces   ( 0 );
    }
    outlet
    {
        type    patch;
        faces   ( 1 );
    }

    sides
    {
        type    patch;
        faces   ( 2 3 );
    }

    ...

- After a mesh is defined, it is trivial to retrieve mesh-related
  information such as cell-volume, cell-centres for any i-j-k location
  without an actual polyMesh.

STYLE: remove -noFunctionObjects from blockMesh

- no time loop, so function objects cannot be triggered anyhow.

tutorials/mesh/PDRblockMesh/box0/Allrun

@@ -0,0 +1,8 @@
+#!/bin/sh
+cd ${0%/*} || exit 1                        # Run from this directory
+. $WM_PROJECT_DIR/bin/tools/RunFunctions    # Tutorial run functions
+
+runApplication PDRblockMesh
+runApplication checkMesh
+
+#------------------------------------------------------------------------------

tutorials/mesh/PDRblockMesh/box0/system/PDRblockMeshDict

@@ -0,0 +1,78 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  v1812                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    object      PDRblockMeshDict;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+//- Point scaling (optional)
+scale 1.0;
+
+x
+{
+    points  ( -13.28 -0.10 6.0 19.19 );
+    nCells  ( 10 12 10 );
+    ratios  ( -5.16 1 5.16 );
+}
+
+y
+{
+    points  ( -12.98 0 5.50 18.48 );
+    nCells  ( 10 11 10 );
+    ratios  ( -5.16 1 5.16 );
+}
+
+z
+{
+    points  ( 0.00 4.80 17.26 );
+    nCells  ( 10 10 );
+    ratios  ( 1 5.16 );
+}
+
+
+defaultPatch
+{
+    name    walls;
+    type    wall;
+}
+
+
+// Faces: 0=x-min, 1=x-max, 2=y-min, 3=y-max, 4=z-min, 5=z-max
+
+boundary
+(
+    outer
+    {
+        type    patch;
+        faces   ( 0 1 2 3 5 );
+    }
+
+    mergingFaces
+    {
+        type    wall;
+        faces   ();
+    }
+
+    blockedFaces
+    {
+        type    wall;
+        faces   ();
+    }
+
+    ground
+    {
+        type    wall;
+        faces   ( 4 );
+    }
+);
+
+// ************************************************************************* //

tutorials/mesh/PDRblockMesh/box0/system/controlDict

@@ -0,0 +1,51 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  v1812                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    location    "system";
+    object      controlDict;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+libs            ("libblockMesh.so");
+
+application     PDRblockMesh;
+
+startFrom       startTime;
+
+startTime       0;
+
+stopAt          endTime;
+
+endTime         0;
+
+deltaT          0;
+
+writeControl    timeStep;
+
+writeInterval   1;
+
+purgeWrite      0;
+
+writeFormat     ascii;
+
+writePrecision  8;
+
+writeCompression off;
+
+timeFormat      general;
+
+timePrecision   6;
+
+runTimeModifiable true;
+
+
+// ************************************************************************* //

tutorials/mesh/PDRblockMesh/box0/system/fvSchemes

@@ -0,0 +1,37 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  v1812                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    location    "system";
+    object      fvSchemes;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+ddtSchemes
+{}
+
+gradSchemes
+{}
+
+divSchemes
+{}
+
+laplacianSchemes
+{}
+
+interpolationSchemes
+{}
+
+snGradSchemes
+{}
+
+
+// ************************************************************************* //

tutorials/mesh/PDRblockMesh/box0/system/fvSolution

@@ -0,0 +1,18 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  v1812                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    location    "system";
+    object      fvSolution;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// ************************************************************************* //