Properly support chord inversions

While I did change a lot of functionality, I also ran `elm-format` across the
codebase, which makes these changes a bit noisy.

Here is the TL;DR:
- Properly support chord inversions
- Ensure that the piano styling changes dynamically when I change the variables
  like `naturalWidth`
- Add start and end notes to define the size of the piano and which chords we
  create
- Support elm-format and run it across entire project
- Debug Misc.comesBefore
- Introduce a ChordInspector and debugger

TODO: Ensure that we only generate chords where all of the notes can be rendered
on the displayed keys.

TODO: Add preferences panel, so that I can do things like "Practice blues chords
in C and E with chord substitutions."

website/sandbox/chord-drill-sergeant/elm.json

@@ -12,6 +12,7 @@
             "elm/random": "1.0.0",
             "elm/time": "1.0.0",
             "elm-community/list-extra": "8.2.3",
+            "elm-community/maybe-extra": "5.2.0",
             "elm-community/random-extra": "3.1.0"
         },
         "indirect": {