API change

Former-commit-id: 1103392dc3571f38f1a33a3b990718ad0e32b45d
comments

Former-commit-id: f99b96076edfa451295245a41691f0a27ab4217b
Add new sample PDF
Update samples
update resources
update resources
update changelog
Use Module
Merge branch 'master' into devel
PSPDFKit 3.5.1 - New property in `PSPDFStyleManager` to customize if annotation changes are saved as new default, better control over the save process, improved compatibility for embedded files, preserves PDF metadata, improves compatibility with annotation writing, the `PSPDFGallery` can now display YouTube videos and various minor improvements and bug fixes.