v2.0.1: two-key structure

What's Changed

• Update to v2.0.1: two-key structure by @not-a-feature in #13
  This will:
  • update to new dict structure
    • Instead of using a combined key (matrix["AX"]) two separate keys are used (matrix["A"]["X"]).
  • add macos to the tests
  • update and improve tests
    • update to the new two-key structure and add a test using a asymmetric matrix.
  • update readme and dependencies page
  • bump version to 2.0.1

Full Changelog: v1.2.2...v2.0.1