fix #40846: require Ctrl+drag to create staff-only barline change
fix #31856: add option to trim whitespace from exported PNG
add chord symbol style options: full german, french, lwoer case bass, all caps note names
Merge pull request #1526 from MarcSabatella/international-chords

add chord symbol style options: full german, french, lower case bass, ...
Merge pull request #1510 from MarcSabatella/40846-ctrl-barline

fix #40846: require Ctrl+drag to create staff-only barline change
fix mtest
Merge pull request #1514 from MarcSabatella/trim-option

fix #31856: add option to trim whitespace from exported PNG