- Fixed notation of note values below C0 in pitches.h (now NOTE_CM1 instead of NOTE_C-1, M for minus) and usage of these in synth.ino.
- Corrected spelling in README.
Revert "- Fixed notation of note values below C0 in pitches.h (now NOTE_CM1 instead of NOTE_C-1, M for minus) and usage of these in synth.ino."

This reverts commit 4f3346a79c5d421f847dcaab90964cf633704e56.
Re-commit:
- Fixed notation of note values below C0 in pitches.h (now NOTE_CM1 instead of NOTE_C-1, M for minus) and usage of these in synth.ino.
- Corrected spelling in README.