fix guitarpro mtests
Merge pull request #1216 from MarcSabatella/gptest-update

fix guitarpro mtests
fix warnings reg. set but unused variables

and remove/comment some other unused ones too
fix some pre-translation issues
add more shortcuts in default drumset
fix #30666: Parts dialog shows no part names after parts are generated
Merge pull request #1213 from Jojo-Schmitz/translation

fix some pre-translation issues
Merge pull request #1217 from Jojo-Schmitz/warnings

fix warnings reg. set but unused variables