10 hole diatonic harmonicas: Add missing keys

When selecting a 10 hole diatonic harmonica, MuseScore only offers the following keys: C, High G, F, D, A, G and Low D. It would be nice to have other keys available as well: D flat, E, E flat, A flat, B flat (vital when playing in second position), and Low F. Without these keys it's very hard to score a lot of harmonica tunes, and/or the lower notes are falsely flagged as out of range, when they're not.