createNonConformalCouples: Put non-conformal couple settings in a sub dictionary

Settings for the individual non-conformal couples can now be put in a
"nonConformalCouples" sub-dictionary of the
system/createNonConformalCouplesDict. For example:

    fields  no;

    nonConformalCouples // <-- new sub-dictionary
    {
        nonConformalCouple_none
        {
            patches         (nonCouple1 nonCouple2);
            transform       none;
        }

        nonConformalCouple_30deg
        {
            patches         (nonCoupleBehind nonCoupleAhead);
            transform       rotational;
            rotationAxis    (-1 0 0);
            rotationCentre  (0 0 0);
            rotationAngle   30;
        }
    }

This permits settings to be #include-d from files that themselves
contain sub-dictionaries without the utility treating those
sub-dictionaries as if they specify a non-conformal coupling. It also
makes the syntax more comparable to that of createBafflesDict.

The new "nonConformalCouples" sub-dictionary is optional, so this change
is backwards compatible. The new syntax is recommended, however, and all
examples have been changed accordingly.

applications/utilities/mesh/manipulation/createNonConformalCouples/createNonConformalCouples.C

@@ -357,7 +357,10 @@ int main(int argc, char *argv[])
 
         fields = dict.lookupOrDefault<bool>("fields", false);
 
-        forAllConstIter(dictionary, dict, iter)
+        const dictionary& couplesDict =
+            dict.optionalSubDict("nonConformalCouples");
+
+        forAllConstIter(dictionary, couplesDict, iter)
         {
             if (!iter().isDict()) continue;