ENH: writeCellCentres: added region option

applications/utilities/postProcessing/miscellaneous/writeCellCentres/writeCellCentres.C

@@ -43,13 +43,14 @@ using namespace Foam;
 int main(int argc, char *argv[])
 {
     timeSelector::addOptions();
+#   include "addRegionOption.H"
 
 #   include "setRootCase.H"
 #   include "createTime.H"
 
     instantList timeDirs = timeSelector::select0(runTime, args);
 
-#   include "createMesh.H"
+#   include "createNamedMesh.H"
 
     forAll(timeDirs, timeI)
     {