ex5: set prefix to DMs to distinguish them also in output file

ex5: tests 2,2a view also partitioned DM

DMPlex tutorial ex5: tests 2,2a use simple partitioner

tests: disable chaco tests when trilinos is used as they produce different results.

Plex ex3: Test does not work with single precision

Plex ex23: Added a test updating the auxdm from the primary dm

Plex ex23: Named test vectors
- Mysteriously, values have changed in the second test

Merge branch 'haplav/feature-dmplex-distributed-hdf5-read' [PR #896]

* haplav/feature-dmplex-distributed-hdf5-read:
Implemented DMPlexLoad_HDF5_Xdmf_Internal which reads the XDMF-related HDF5 groups

Merge branch 'haplav/feature-dmplex-distributed-hdf5-read' [PR #896]

* haplav/feature-dmplex-distributed-hdf5-read:
Implemented DMPlexLoad_HDF5_Xdmf_Internal which reads the XDMF-related HDF5 groups for topology and geometry locally.
New formats PETSC_VIEWER_HDF5_{PETSC,XDMF} controlling both DMLoad and DMView:
PETSC_VIEWER_HDF5_PETSC, PETSC_VIEWER_HDF5_XDMF, PETSC_VIEWER_HDF5_VIZ, PETSC_VIEWER_DEFAULT.

show more ...

plex tutorial ex5: updated test requirements

DMPlexLoad_HDF5_Xdmf_Internal: fix for complex PetscScalar.

Convert coordinates_arr to PetscReal if needed.

DMPlexLoad_HDF5_Xdmf_Internal: fix for 64-bit PetscInt.

Convert cells_arr to 32-bit int if needed.

DMPlexBuildFromCellList_Internal: use DMPlexInvertCell_Internal (with PetscInt* arg)

DMPlexCreateFromFile: document option

check only if PETSC_USE_DEBUG

DMPlexBuildFromCellList_Internal optionally inverts cells.

To unify it with DMPlexBuildFromCellList_Parallel_Internal.

ex5: new test 4 with -compare without repartitioning

ex5: new test 3 using -compare

ex5: HDF5 write+read moved to separate function

ex5: option -format processed in ProcessOptions()

ex5: added missing hdf5 requirement

DMPlexLoad_HDF5_Xdmf_Internal inverts cells.

DMPlexBuildFromCellList_Parallel_Internal optionally inverts cells.

ex5: -distribute option toggles distribution

DMPlexLoad_HDF5_Xdmf_Internal reads labels w/ DMPlexLoadLabels_HDF5_Internal.

DMPlexLoadLabels_HDF5_Internal factored out from DMPlexLoad_HDF5_Internal.

DMPlexLoad_HDF5_Xdmf_Internal: check max index in cells

ex5: tests 0 and 1 updated and activated.