Give the music lab some love

[SLUCHABLUB]

I've implemented some of the things I had in mind. Some changes may be more "controversial" than others so I'm prepared to cherry pick the commits.

TO-DO list:

• Run scala fmt
• Remove Scala 2 syntax
• Use scientific pitch notation (middle C is C4 not C5)
• Remove some unneeded brackets.
• Use math.floorMod when calculating relativePitchClasses
  Lest I'm mistaken, (i % 12 + 12) % 12 and floorMod(i, 12) do the same thing.
• import stuff
  There are a lot of places where objects are fully qualified. I think it would be more readable if they were imported.
• Use more standard music terminology.
  For example change "relative pitch classes" to "simple intervals".
• Rework some names
  Some names are (in my opinion) unnecessarily compressed. Whilst I can accept the use of single letter names (at least outside of public API), I would like to change nbrOf* and to*Opt to numberOf* and to*Option to align with the naming in std.
• Use enums in place of Ints
  There is a nauseatingly high usage of integers throughout the lab for things that should be enums. On one hand it could prompt students to refactor the api themselves. On the other hand we should encourage the use of enums and in my my experience most people are quite cautious when it comes to changing the given code.
• Update the compendium
  The compendium needs to be updated to reflect (some of) the above changes.

[bjornregnell]

Thank you for your work on this! Let's discuss on the lecture breaks the coming week.