hdf5

Merge pull request #1972 in HDFFV/hdf5 from ~BYRN/hdf5_adb:hdf5_1_10 to hdf5_1_10

* commit '87977eab7d178e4f3b9ba2cd5b97812d594ae105':
  HDFFV-10919 merge synching
  HDFFV-10408,10918 add note
  HDFFV-10918 External Storage test files added
  Whitespace and benign synchro changes