Further improvements to hdf5 unpack_data.
Further improvements to hdf5 unpack_data.

More vectorized operations.

BlueBrain/NeuroM,juanchopanza/NeuroM,lidakanari/NeuroM,liesbethvanherpe/NeuroM,wizmer/NeuroM,mgeplf/NeuroM,eleftherioszisis/NeuroM