hdf5

Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop)

* commit '1db039d1beee05d7349e153cef4cf642c907cc1e':
  Fixed h5diff command-line parameters to use 1 and 2 instead of src and dst.
  Added VOL command-line options to (p)h5diff, h5ls, h5dump, and h5mkgrp.