ENH: add moveMesh -deltaT option

- overrides normal deltaT for testing accelerated motion.

  Can be useful to test mesh motions with constant/dynamicMeshDict
  entries (updateControl, updateInterval) where the mesh motion is
  much slower than any of the fluid physics.

  see commit 87bba9ae14

applications/utilities/mesh/manipulation/moveMesh/moveMesh.C

@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -50,10 +51,23 @@ int main(int argc, char *argv[])
         "A solver utility for moving meshes"
     );
 
+    argList::addOption
+    (
+        "deltaT",
+        "time",
+        "Override deltaT for accelerated motion"
+    );
+
     #include "setRootCase.H"
     #include "createTime.H"
     #include "createNamedMesh.H"
 
+    scalar deltaT = 0;
+    if (args.readIfPresent("deltaT", deltaT))
+    {
+        runTime.setDeltaT(deltaT);
+    }
+
     autoPtr<motionSolver> motionPtr = motionSolver::New(mesh);
 
     while (runTime.loop())