IOobject: Added modelName member function

which constructs the name for a field property associated with the model by
pre-pending the given field name with <modelType>: e.g. the generation term in
the kEpsilon model is named kEpsilon:G

src/OpenFOAM/db/IOobject/IOobject.H

@@ -372,6 +372,10 @@ public:
             //- Return member (name without the extension)
             word member() const;
 
+            //- Return the name of the object within this model
+            //  as <model>:<name>
+            inline word modelName(const char* name) const;
+
             const fileName& rootPath() const;
 
             const fileName& caseName() const;

src/OpenFOAM/db/IOobject/IOobjectI.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -41,6 +41,12 @@ inline Foam::word Foam::IOobject::groupName(Name name, const word& group)
 }
 
 
+inline Foam::word Foam::IOobject::modelName(const char* name) const
+{
+    return type() + ':' + name;
+}
+
+
 template<class Stream>
 inline Stream& Foam::IOobject::writeBanner(Stream& os, bool noHint)
 {