fix build of plugins manual
Added support for voltas in Guitar Pro 4 files
Support for voltas in Gutiar Pro 3 files
fix #22898 - tests to verify voltas are being imported correctly in Guitar Pro files
test to fix #25559: show splash screen on linux
Merge pull request #867 from Jojo-Schmitz/plugins-manual

fix build of plugins manual
Merge pull request #869 from triolenzunge/25559-showsplash

test to fix #25559: show splash screen on linux
Merge pull request #868 from jpirie/22898-guitar-pro-volta

Volta support in GP3 and GP4 files