v0.1.3

[juk0de]

• implemented new CLI options --mtf-dir and --json-dir
  • can be used to convert all MTF files in a directory
• --convert is automatically enabled if:
  • --json-file or --json-dir are specified
  • more than one argument has been passed with --mtf-file
• implemented CLI tests
  • see test_cli.py
• fixed the mypy stub for mtf2json.py
• configured Github actions
  • building, linting with flake8, testing with pytest and pytest-cov