export xdmf for import into vtk

extracted with:
    sha1=975536e3d94f08b06b002452a5ed575dc6eb0fc9 &&
    paths='
    CMake
    CMakeLists.txt
    CTestConfig.cmake
    Copyright.txt
    Xdmf.hpp
    XdmfAttribute.cpp
    XdmfAttribute.hpp
    XdmfAttributeCenter.cpp
    XdmfAttributeCenter.hpp
    XdmfAttributeType.cpp
    XdmfAttributeType.hpp
    XdmfConfig.cmake.in
    XdmfCurvilinearGrid.cpp
    XdmfCurvilinearGrid.hpp
    XdmfDomain.cpp
    XdmfDomain.hpp
    XdmfGeometry.cpp
    XdmfGeometry.hpp
    XdmfGeometryType.cpp
    XdmfGeometryType.hpp
    XdmfGraph.cpp
    XdmfGraph.hpp
    XdmfGrid.cpp
    XdmfGrid.hpp
    XdmfGridCollection.cpp
    XdmfGridCollection.hpp
    XdmfGridCollectionType.cpp
    XdmfGridCollectionType.hpp
    XdmfItemFactory.cpp
    XdmfItemFactory.hpp
    XdmfMap.cpp
    XdmfMap.hpp
    XdmfReader.cpp
    XdmfReader.hpp
    XdmfRectilinearGrid.cpp
    XdmfRectilinearGrid.hpp
    XdmfRegularGrid.cpp
    XdmfRegularGrid.hpp
    XdmfSet.cpp
    XdmfSet.hpp
    XdmfSetType.cpp
    XdmfSetType.hpp
    XdmfTime.cpp
    XdmfTime.hpp
    XdmfTopology.cpp
    XdmfTopology.hpp
    XdmfTopologyType.cpp
    XdmfTopologyType.hpp
    XdmfUnstructuredGrid.cpp
    XdmfUnstructuredGrid.hpp
    core/CMakeLists.txt
    core/XdmfArray.cpp
    core/XdmfArray.hpp
    core/XdmfArray.tpp
    core/XdmfArrayReference.cpp
    core/XdmfArrayReference.hpp
    core/XdmfArrayType.cpp
    core/XdmfArrayType.hpp
    core/XdmfBinaryController.cpp
    core/XdmfBinaryController.hpp
    core/XdmfConfig.hpp.in
    core/XdmfCore.hpp
    core/XdmfCoreItemFactory.cpp
    core/XdmfCoreItemFactory.hpp
    core/XdmfCoreReader.cpp
    core/XdmfCoreReader.hpp
    core/XdmfError.cpp
    core/XdmfError.hpp
    core/XdmfFunction.cpp
    core/XdmfFunction.hpp
    core/XdmfHDF5Controller.cpp
    core/XdmfHDF5Controller.hpp
    core/XdmfHDF5Writer.cpp
    core/XdmfHDF5Writer.hpp
    core/XdmfHeavyDataController.cpp
    core/XdmfHeavyDataController.hpp
    core/XdmfHeavyDataWriter.cpp
    core/XdmfHeavyDataWriter.hpp
    core/XdmfInformation.cpp
    core/XdmfInformation.hpp
    core/XdmfItem.cpp
    core/XdmfItem.hpp
    core/XdmfItemProperty.cpp
    core/XdmfItemProperty.hpp
    core/XdmfSharedPtr.hpp
    core/XdmfSparseMatrix.cpp
    core/XdmfSparseMatrix.hpp
    core/XdmfSubset.cpp
    core/XdmfSubset.hpp
    core/XdmfSystemUtils.cpp
    core/XdmfSystemUtils.hpp
    core/XdmfVisitor.cpp
    core/XdmfVisitor.hpp
    core/XdmfWriter.cpp
    core/XdmfWriter.hpp
    core/loki
    core/dsm/CMakeLists.txt
    core/dsm/XdmfDSM.hpp
    core/dsm/XdmfDSMBuffer.cpp
    core/dsm/XdmfDSMBuffer.hpp
    core/dsm/XdmfDSMCommMPI.cpp
    core/dsm/XdmfDSMCommMPI.hpp
    core/dsm/XdmfDSMDriver.cpp
    core/dsm/XdmfDSMDriver.hpp
    core/dsm/XdmfDSMManager.cpp
    core/dsm/XdmfDSMManager.hpp
    core/dsm/XdmfHDF5ControllerDSM.cpp
    core/dsm/XdmfHDF5ControllerDSM.hpp
    core/dsm/XdmfHDF5WriterDSM.cpp
    core/dsm/XdmfHDF5WriterDSM.hpp
    ' &&
    git archive --prefix=xdmf3-reduced/ $sha1 -- $paths |
    tar x

Change-Id: I8c3dd91dc165a592f7dc3d2898ddf1d18db45811