Added IOobject::readOption to IOOutputFilter

- allows post-processing functions with an optional dictionary
   (eg, the developer can hard-wire some defaults)

src/sampling/outputFilters/IOOutputFilter/IOOutputFilter.C

@@ -34,6 +34,7 @@ Foam::IOOutputFilter<OutputFilter>::IOOutputFilter
 (
     const objectRegistry& obr,
     const fileName& dictName,
+    const IOobject::readOption rOpt,
     const bool readFromFiles
 )
 :
@@ -44,7 +45,7 @@ Foam::IOOutputFilter<OutputFilter>::IOOutputFilter
             dictName,
             obr.time().system(),
             obr,
-            IOobject::MUST_READ,
+            rOpt,
             IOobject::NO_WRITE
         )
     ),

src/sampling/outputFilters/IOOutputFilter/IOOutputFilter.H

@@ -70,11 +70,13 @@ public:
     // Constructors
 
         //- Construct for given objectRegistry and dictionary
-        //  allow the possibility to load fields from files
+        //  Allow dictionary to be optional
+        //  Allow the possibility to load fields from files
         IOOutputFilter
         (
             const objectRegistry&,
             const fileName& dictName = OutputFilter::typeName() + "Dict",
+            const IOobject::readOption rOpt = IOobject::MUST_READ,
             const bool loadFromFile = false
         );