[GSoC] Set up HDF5 file structure for datasets

[gabrielasd]

Modify the current Python code to store the atomic species data (e.g., electronic configurations, electronic density properties, etc.) in an HDF5 structure. Enable initialization of a Species instance from this HDF5 file.

For each dataset (e.g., gaussian, nist, etc.), the goal is to have a single HDF5 file per element. For example for Carbon atom, the HDF5 file would have the rough structure:

├── C
    ├── C_-01_004_000
    │   ├── Table(s)
    ├── C_-02_003_000
    │   ├── Table(s)
...

Module associated with this change: species.py

Some of the methods/functions that are expected to change are:
SpeciesData
Species
load
dump

Tasks

• Design HDF5 structure for species datasets.
• Add methods to load and read data from HDF5 files
• Modify species.py module to initialize a Species from HDF5 data and dump an instance of Species to an HDF5 file
• Add tests