Fix undesired _ = None | None = _ style warnings
_ = Some _ | Some _ = _ option style violations now. Match Case Improvements (PR#81)
* Improved student-facing "fix" for `x :: []` match patterns.
Now includes the preferred syntax (`[x]`) that should be used
in place of the above.
* Added new tests for the match patterns.
* Add ocaml.4.11.1 to CI runners.
* Added CHANGELOG.md (finally)