ENH: Adding dimensioSet to DataEntry and modify MRFZone entry types

src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.C

@@ -154,6 +154,16 @@ dimensioned<Type>::dimensioned
 }
 
 
+template <class Type>
+dimensioned<Type>::dimensioned
+()
+:
+    name_("undefined"),
+    dimensions_(dimless),
+    value_(pTraits<Type>::zero)
+{}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template <class Type>

src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.H

@@ -107,6 +107,9 @@ public:
         //- Construct from an Istream with a given name and dimensions
         dimensioned(const word&, const dimensionSet&, Istream&);
 
+        //- Null constructor
+        dimensioned();
+
         //- Construct from dictionary, with default value.
         static dimensioned<Type> lookupOrDefault
         (