snappyHexMeshConfig: added '-noBackground' option to prevent writing of a blockMeshDict file

applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfig.C

@@ -107,6 +107,9 @@ Usage
       - \par -cylindricalBackground
         Generate a cylindrical background mesh aligned with the z-axis
 
+      - \par -noBackground
+        Do not write a blockMeshDict file
+
       - \par -refineBackground \<int\>
         Integer multiplier for the number of cells (>= 1)
 
@@ -245,6 +248,12 @@ int main(int argc, char *argv[])
         "generate a cylindrical background mesh aligned with the z-axis"
     );
 
+    argList::addBoolOption
+    (
+        "noBackground",
+        "do not write a blockMeshDict file"
+    );
+
     argList::addOption
     (
         "refineBackground",
@@ -513,6 +522,8 @@ int main(int argc, char *argv[])
 
     const bool clearBoundary(args.optionFound("clearBoundary"));
 
+    if (!args.optionFound("noBackground"))
+    {
         if (args.optionFound("cylindricalBackground"))
         {
             blockMeshCylindricalConfiguration blockMeshConfig
@@ -547,6 +558,7 @@ int main(int argc, char *argv[])
 
             blockMeshConfig.write();
         }
+    }
 
     // snappyHexMeshDict options
     const label refinementLevel