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/shell.nix

@@ -3,5 +3,6 @@ let
 in pkgs.mkShell {
   buildInputs = with pkgs; [
     elmPackages.elm
+    elmPackages.elm-format
   ];
 }