fix #33081: acoustic bass channel info
Style of the initial bar line of a system.

In some engraving styles (mainly jazz), a double system initial bar line is used at structural articulations of the piece.

The PR supports this style, by adding a `_systemInitialBarLineStyle` variable to the `Measure` class which controls the style of the system bar line when the measure is the first of the system and by default it is set to NORMAL. This variable is not accessed directly; rather it is controlled by manipulating the system bar line. A system bar line can be edited:

- by dropping on it a bar line style from the palette (structural styles, like any repeat or END are ignored);
- by selecting it and double clicking a bar line style from the palette (same note as above).

It can be reset:

- by undo;
- by dropping on it (or selecting and double clicking) a NORMAL bar line style from the palette;
- by selecting and deleting it.

As the system bar line style is stored in the measure, if the first measure of a system changes (because of some other editing), the system bar line style will follow accordingly.
fix #32651: Naturals should not be shown at system break
fix #38501: cheap partial fix for start position of cross-staff and cross-system gliss
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
fix #38766: bad input position after timesig change
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 #38891: phantom measures after delete all in continuous view
fix for pointer size when casting to integer in the debugger
fix #38486
add thumbnails, more code for startcenter
convert templates to mscz + thumbnail
startcenter: implement templates+demos