0.3.0

• Decays modelling:
  • Updates to Mint related particle data files.
• Parsing of decay files (aka .dec files):
  • Lark parser files added, for .dec decay files.
  • DecFileParser class introduced, with documentation and test suite.
  • Various .dec test decay files added.
• Visualisation of decay chains:
  • DecayChainViewer class introduced, with documentation and test suite.
• Universal representation of decay chains:
  • First "building block" classes DaughtersDict and DecayMode introduced,
    with documentation and test suite.
• Package dependencies:
  • Package made dependent on Scikit-HEP's Particle package.
  • Redundant code removed.
• Continuous integration:
  • CI with Azure pipelines introduced.
  • CI with Travis and AppVeyor removed.
• Miscellaneous:
  • Demo notebook added, with a launcher for Binder.
  • Copyright statements added to repository files.
  • General clean-up and minor bug fixes.