fix #38501: cheap partial fix for start position of cross-staff and cross-system gliss
fix #38731: Beams connected to irregular tuplets in a 4/4 time signature and on beats one and three are incorrect
fix mtest
fix #38816: crash on delete all of empty score with title frame
Merge pull request #1448 from MarcSabatella/38816-delete-all-empty

fix #38816: crash on delete all of empty score with title frame
Merge pull request #1439 from MarcSabatella/38501-cross-staff-gliss

fix #38501: cheap partial fix for cross-staff and cross-system gliss
fix possible crash when layouting glissando when chord has dot but notes doesn't because in a tabstaff
try workspace selector at the bottom, fix margins
remove icons in plugin creator menu
Move MIDI import files to importmidi/ dir
Replace Windows line endings (CRLF) with LF in MIDI import files
Merge pull request #1450 from trig-ger/midi_dir

Move MIDI import files to importmidi/ dir
fix #38486
add thumbnails, more code for startcenter
convert templates to mscz + thumbnail
startcenter: implement templates+demos
fix warning and untranslate "about:blank"