fix #40066: use es/is for german chords if lower case option enabled
Merge pull request #1509 from MarcSabatella/pure-german

fix #40066: use es/is for german chords if lower case option enabled
don't implode voices of different rhythms

as this it can lead to data loss.
On imploding staves it could lead to some incorrectness, but as the old
staves are still there, this can get spotted and fixed.