including the merge of `hdffv/hdf5/develop`, back to the branch that Vailin and
I share.
Now I need to put this branch on a fork with a less confusing name than
vchoi_fork!
compatible between 32 and 64 bit systems.
Expand cross platform property list encode/decode testing.
Fix warning in H5P__fill_value_enc.
Tested: jam, koala, ostrich (h5committest), ummon