ENH: simple dataCloud function object (issue #1044)

- writes positions and a single field (eg, diameter) in plain ASCII files,
  suitable for importing in a spreadsheet or manipulation with
  scripting tools.

- code integrated from
  https://develop.openfoam.com/Community/OpenFOAM-addOns

tutorials/lagrangian/coalChemistryFoam/simplifiedSiwek/system/controlDict

@@ -54,6 +54,7 @@ maxDeltaT       1;
 functions
 {
     #include "vtkCloud"
+    // #include "dataCloud"
     #include "runTimePostProcessing"
 }
 

tutorials/lagrangian/coalChemistryFoam/simplifiedSiwek/system/dataCloud

@@ -0,0 +1,13 @@
+// -*- C++ -*-
+// Minimal example of using the dataCloud function object.
+dataCloud
+{
+    type    dataCloud;
+    libs    ("liblagrangianFunctionObjects.so");
+    log     true;
+
+    cloud   coalCloud1;
+    field   d;
+}
+
+// ************************************************************************* //