ENH: add directionalMeshWave functionality

For a given point within a given mesh, the existing `meshWave` method gives
  the orthogonal distance to a patch. In meshes with very steep terrain (e.g.
  a hill of 90 [deg], this might be problematic for the fields that require
  the distance to the patch associated with the terrain surface.

  `directionalMeshWave` is a variant of `meshWave` distance-to-patch method,
  which ignores the component in the specified direction. Can be used e.g. to
  calculate the distance in the z-direction only.

  TUT: add example of directionalMeshWave to mesh/moveDynamicMesh/SnakeCanyon

  Requirement by CENER
  Implementation by Mattijs Janssens

src/meshTools/cellDist/patchWave/patchDataWave.H

@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -62,7 +63,7 @@ class wallPoint;
                         Class patchDataWave Declaration
 \*---------------------------------------------------------------------------*/
 
-template<class TransferType>
+template<class TransferType, class TrackingData = int>
 class patchDataWave
 :
     public cellDistFuncs
@@ -84,6 +85,10 @@ private:
         //- Do accurate distance calculation for near-wall cells.
         bool correctWalls_;
 
+        //- Additional data to be passed into underlying containers
+        TrackingData& td_;
+
+
         //
         // After construction:
         //
@@ -115,7 +120,14 @@ private:
         ) const;
 
         //- Copy MeshWave values into *this
-        label getValues(const MeshWave<TransferType>&);
+        label getValues(const MeshWave<TransferType, TrackingData>&);
+
+
+  // Private static data
+
+        //- Used as default trackdata value to satisfy default template
+        //  argument.
+        static int dummyTrackData_;
 
 
 public:
@@ -131,7 +143,8 @@ public:
             const polyMesh& mesh,
             const labelHashSet& patchIDs,
             const UPtrList<Field<Type>>& initialPatchValuePtrs,
-            bool correctWalls = true
+            const bool correctWalls = true,
+            TrackingData& td = dummyTrackData_
         );