Small optimization in hdf5 unpack_data
Small optimization in hdf5 unpack_data

* Use numpy operations to build raw data block.

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