adding compass example

[FoamyGuy]

This adds the compass example from the old PR referenced in issue #2

[caternuson]

@FoamyGuy I restarted the CI run on your last commit. It was failing due to 404s when installing deps that just got fixed in another repo.

Now it's failing for pylint reasons. In case you don't know the trick, just unpack the unused z into _.

    magnet_x, magnet_y, _ = _sensor.magnetic

[FoamyGuy]

@caternuson Thank you. I did not know the underscore trick, thank you for that as well. I've updated the code with that change.

[caternuson]

Looks good!