hdf5

Merge pull request #650 in HDFFV/hdf5 from ~BYRN/hdf5_adb:hdf5_1_8 to hdf5_1_8

* commit '8b910ce2d626d6cd03efb92db3b9fe008d163323':
  HDFFV-10276 restore argument spacing
  Fix extra whitespace in usage() text
  HDFFV-10276 add whitespace
  HDFFV-10276 correct typo
  HDFFV-10276 Correct note of change in UD parameters
  HDFFV-9774 Add note to new argument
  HDFFV-10276 add enable-error-stack to h5diff