PyHDX version 0.4.0

Release v0.4.0 is the combination of 9 beta versions, spanning a total of ~10 months of PyHDX development.
Please refer to the individual beta releases for more detail.

Major improvements of the new version 0.4.0 release are:

Base PyHDX:

• Batch fitting of multiple large HDX datasets (+ GPU support)
• Batch processing of large HDX datasets through .yaml file spec
• Added $pyhdx process CLI command (early alpha feature)
• Added plotting and pdf output modules
• Major API changes

PyHDX-web:

• Two complete overhauls of the web interface, improving internal logic of the web interface
• Updated the GoldenLayout template to a combination of panel's GoldenLayout and the elvis golden layout
• Addition of the PDBeMolstar protein viewer, allowing direct export of colored structures
• Direct output of publication quality graphs from the web interface
• Create differential HDX datasets (ΔΔG / ΔRFU)

This release:

• Updated docs and docstrings, introduced PEP483 type hints (#271)
• Update to panel version 0.13.0 (#264)
• Added black, mypy, flake8, (isort) linters