hdf5

Merge pull request #2027 in HDFFV/hdf5 from ~DYOUNG/hdf5:dsets-randomness to develop

* commit '4d834adba4aeb1a0174bddb83212b7073b64e269':
  Use HD prefix.
  Fix HDFFV-10937: use a more reliable (and probably faster) scheme for visiting all elements of a matrix in an arbitrary order.