STYLE: use range-for when looping dictionary entries.

- as part of the cleanup of dictionary access methods (c6520033c9)
  made the dictionary class single inheritance from IDLList<entry>.

  This eliminates any ambiguities for iterators and allows
  for simple use of range-for looping.

  Eg,
      for (const entry& e : topDict))
      {
          Info<< "entry:" << e.keyword() << " is dict:" << e.isDict() << nl;
      }

   vs

      forAllConstIter(dictionary, topDict, iter))
      {
          Info<< "entry:" << iter().keyword()
              << " is dict:" << iter().isDict() << nl;
      }

src/parallel/decompose/decompositionMethods/decompositionMethod/decompositionMethod.C

@@ -125,9 +125,9 @@ void Foam::decompositionMethod::readConstraints()
 
     if (dictptr)
     {
-        forAllConstIters(*dictptr, iter)
+        for (const entry& dEntry : *dictptr)
         {
-            const dictionary& dict = iter().dict();
+            const dictionary& dict = dEntry.dict();
 
             constraintTypes.append(dict.get<word>("type"));