use dictionary::readIfPresent wherever reasonable

src/OpenFOAM/db/IOobject/IOobjectReadHeader.C

src/OpenFOAM/db/IOobject/IOobjectWriteHeader.C

src/OpenFOAM/db/Time/Time.C

src/OpenFOAM/db/Time/TimeIO.C

src/OpenFOAM/matrices/lduMatrix/lduMatrix/lduMatrix.H

src/OpenFOAM/matrices/lduMatrix/lduMatrix/lduMatrixSolver.C

...penFOAM/matrices/lduMatrix/lduMatrix/lduMatrixTemplates.C

...x/preconditioners/GAMGPreconditioner/GAMGPreconditioner.C

src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGSolver.C

...AM/matrices/lduMatrix/solvers/smoothSolver/smoothSolver.C

src/OpenFOAM/matrices/solution/solution.H

src/OpenFOAM/meshes/patchIdentifier/patchIdentifier.C

.../polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C

...FOAM/meshes/polyMesh/polyPatches/polyPatch/newPolyPatch.C

src/OpenFOAM/meshes/preservePatchTypes/preservePatchTypes.C

...xMesh/autoHexMeshDriver/layerParameters/layerParameters.C

src/conversion/ensight/part/ensightPart.C

src/conversion/meshReader/starcd/STARCDMeshReader.C

...lomeration/decompositionMethods/metisDecomp/metisDecomp.C

...ecompositionAgglomeration/parMetisDecomp/parMetisDecomp.C