Converter: Possibility to specify other names than 'labels', 'features' for the input files
Test convertion from h5features old versions
read/write bigger than RAM -> catch MemoryError when np.concatenate on writing.
labels can be of arbitrary type (optionally sorted)
Have a h5features.File class inspired by h5py.File
Make Data a dict with the following syntax:
with h5f.Reader(file, group) as reader: reader['item'][from_time:to_time] reader['item'].features reader['item'].labels reader.keys()
Make an Item class wrapping Labels and Features
Implement sparse functionalities
Handle h5py MPI driver for concurent reading