functionObjects: Moved into the functionObjects namespace and rationalized and simplified failable construction

Rather than requiring each functionObject to handle failed construction
internally (using the active_ flag) the static member function "viable"
is provided which returns true if construction of the functionObject is
likely to be successful.  Failed construction is then handled by the
wrapper-class which constructs the functionObject,
e.g. "OutputFilterFunctionObject".

src/postProcessing/functionObjects/field/processorField/processorField.H

@@ -22,7 +22,7 @@ License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
 Class
-    Foam::processorField
+    Foam::functionObjects::processorField
 
 Group
     grpFieldFunctionObjects
@@ -76,6 +76,9 @@ class objectRegistry;
 class dictionary;
 class mapPolyMesh;
 
+namespace functionObjects
+{
+
 /*---------------------------------------------------------------------------*\
                        Class processorField Declaration
 \*---------------------------------------------------------------------------*/
@@ -92,9 +95,6 @@ protected:
         //- Reference to the database
         const objectRegistry& obr_;
 
-        //- on/off switch
-        bool active_;
-
 
 private:
 
@@ -125,6 +125,16 @@ public:
             const bool loadFromFiles = false
         );
 
+        //- Return true if the construction of this functionObject is viable
+        //  i.e. the prerequisites for construction are available
+        static bool viable
+        (
+            const word& name,
+            const objectRegistry&,
+            const dictionary&,
+            const bool loadFromFiles = false
+        );
+
 
     //- Destructor
     virtual ~processorField();
@@ -165,6 +175,7 @@ public:
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+} // End namespace functionObjects
 } // End namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //