XR version 0.2.1

• Fixes:
  • The edit sub-command previously rejected not-already-existing notes, while editors are well capable of creating files. It now accepts such deduced or given arguments but still rejects when not being in an exercise's directory.
• Contents:
  • New or updated Benchmarks:
    • pythagorean-triplet
    • protein-translation
    • difference-of-squares
  • New or updated Notes:
    • pythagorean-triplet
    • protein-translation
    • difference-of-squares
    • raindrops
    • gigasecond
    • clock