Fix #23519 - key signatures now correctly supported in older versions of Guitar Pro
Removed unnecessary 0
Fixes to instruments.xml for stringed instruments.

- Banjo: corrected num.of frets and highest string tuning
- Tenor Banjo: added string data
- Soprano guitar, alto guitar, 11-str. alto guitar, 12-string guitar: added string data
- 7-course lute: added string data
- Acoustic bass: added comment about identity wth contrabass
- Violin, viola, cello, contrabass: added string data
- Double bass: init'ed from contrabass
- Violone (G): added string data and corrected ranges
- D Violone: added
fix vtest gen
Merge pull request #952 from mgavioli/instruments-xml_stringed_instr_fixes

Fixes to instruments.xml for stringed instruments.
workaround for #25954
comment process()
fix #25946
fix #25945
fix mtest
Merge pull request #956 from MarcSabatella/vtest-gen

fix vtest gen
Merge pull request #948 from jpirie/23519-key-signatures

Key signature support in older versions of Guitar Pro
remove 'styled' option from header/footer text dialog
updates for page header/footer
make enum class SegmentType a ": short"
convert enum Hidden into global enum class

after having seen how it is done in e1b1246
convert enum AlignmentFlag into enum class
small step further in converting enum Repeat into enum class

not there yet, as at least overloaded operators for |, &, |=, &= and ~ would be needed to make this fully working. And even then it'd require lots of explict casting. This is most probably not be worth the price...
convert enum ElementFlag into enum class
convert enum LayoutFlag into enum class