Internal updates

What's Changed

• Split HDF5 reading tasks from API definition by @callumforrester in #15
• Separate reading logic from multiprocessing by @callumforrester in #18
• Fix all CI jobs except docs failing to run by @callumforrester in #19
• Data Model by @callumforrester in #17
• Additional system tests by @callumforrester in #16
• Move to python3-pip-skeleton by @callumforrester in #21

Full Changelog: 0.1.2...0.1.3