ENH: have MUST_READ_IF_MODIFIED on IOdictionary construction

src/paraview-plugins/PV3Readers/PV3FoamReader/vtkPV3Foam/vtkPV3Foam.C

@@ -444,7 +444,7 @@ void Foam::vtkPV3Foam::updateFoamMesh()
                 meshRegion_,
                 dbPtr_().timeName(),
                 dbPtr_(),
-                IOobject::MUST_READ
+                IOobject::MUST_READ_IF_MODIFIED
             )
         );
 

src/paraview-plugins/PV3Readers/PV3blockMeshReader/vtkPV3blockMesh/vtkPV3blockMesh.C

@@ -315,7 +315,7 @@ void Foam::vtkPV3blockMesh::updateFoamMesh()
                 dbPtr_().constant(),
                 polyMesh::meshSubDir,
                 dbPtr_(),
-                IOobject::MUST_READ,
+                IOobject::MUST_READ_IF_MODIFIED,
                 IOobject::NO_WRITE,
                 false
             )