Concert Pitch switching does not preserve key spelling if the transposition crosses between sharp and flat keys
Steps to reproduce:
1. Create new score for C Trumpet and Bb Trumpet
2. Drag F# major (6 sharps) key signature to first measure of C Trumpet staff
3. Switch to Concert Pitch
Expected behavior: Both staves should be in F# major (6 sharps)
Actual behavior: Bb Trumpet staff is in Gb major (6 flats).
Discussion: This defeats the purpose of the Concert Pitch button (letting the composer/arranger think in a single key).
GIT commit: a315216