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
Merge pull request #1309 from MarcSabatella/33081-bass-arco

fix #33081: acoustic bass channel info
use MusicXML formatting for first page header
header and footer fixes
fix #8924: native support for slash notation
fix #39421: fix selection detection of break plugin

similar to earlier fixes for colornotes (606b401) and notenames
(df6e8a0)
Merge pull request #1461 from Jojo-Schmitz/break-every-x-measures

fix #39421: fix selection detection of break plugin
fix double dialogs when error for login, fix modal message dialog
Merge pull request #1459 from lvinken/musicxml-font-handling

Musicxml font handling
do not init workspace if no UI
fix #36186 : crash when pasting with left-over portion spanning over an invalid duration
fix #39456: double click drum icon enters wrong segment/voice
fix #39476: corruption on entry of drum note onto segment with no element in voice 1
fix #39466: initially selected drum not active
add accent in Basic Palette
implement categories for template files in startcenter
sort score names in startcenter
simplify basic palette further