Instrument icons

The instrument drawings in this app (violin, flute, clarinet, bassoon, saxophone,
french horn, trumpet, trombone, tuba, drum, drum kit, gong, xylophone, grand piano,
pipe organ, harp, microphone, musical score) come from game-icons.net:

  https://game-icons.net
  https://github.com/game-icons/icons

by Lorc, Delapouite and the other game-icons.net contributors, licensed under
Creative Commons Attribution 3.0 Unported (CC BY 3.0):

  https://creativecommons.org/licenses/by/3.0/

They are used unchanged, as inline SVG paths in src/lib/components/InstrumentGlyph.svelte.