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/fieldValues/faceSource/faceSourceFunctionObject.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -43,8 +43,10 @@ SourceFiles
 
 namespace Foam
 {
-    typedef OutputFilterFunctionObject<fieldValues::faceSource>
-        faceSourceFunctionObject;
+    typedef OutputFilterFunctionObject
+    <
+        functionObjects::fieldValues::faceSource
+    > faceSourceFunctionObject;
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //