Prepare for release 1.2.0

[LukeParky]

DESCRIPTION OF PR:

• Updates version numbers
• Adds Martin as a paper author
• Allows Open-Source contributions according to notes in #234 and #209

Developer Checklist

• [ ] Make code change
• [ ] Update tests
  • [ ] Update / create new tests
  • [ ] Ensure these tests have the expected behaviour
  • [ ] Test locally and ensure tests are passing
• [ ] Update documentation
  • [ ] Readme
  • [ ] Docstrings
  • [ ] Comments
  • [ ] Wiki

Reviewer Checklist

• [ ] Check new code for code smells
• [ ] Check new tests
  • [ ] Ensure adequate coverage
  • [ ] Check for code smells within tests
• [ ] Check if documentation needs updating
  • [ ] Readme
  • [ ] Docstrings
  • [ ] Comments
  • [ ] Wiki