* Better handle multiple tags respecting US format
Based on unversioned, V1 & V2 of US formats : https://github.com/UltraStar-Deluxe/format
Should address #623
Creator now takes multiple values
Maintain backward compatibility
* Update file path properties to match US formats
Seems to not be usefull since song is cloned is others game mode
Improve performance by stop reloading TXT file
Didn't see any difference with and without instead of just song load perfs imrpovement
Maybe that I miss a point ?
* Apply R# clean-up for reliability
- Migrate to NUnit4 Assert.That
- Update dependencise versions
- Fix LangVersion to 9.0 (until net core migration)
- Reformat code
- Apply 'var' style (easier for refactoring)
- Remove redundant parentheses
- Add braces on every condition blocks (1 line)
- Uses new null checking patterns
- Uses AutoProperties when possible
- Uses string scalar type instead of class
- Clean usings
- Add .orig files in git ignore
- Rename some properties to respect defined conventions and US format definition
- ID -> Id
- BPM -> Bpm
- Finish -> End
* Update R# settings according to the clean-up made
Quentin Bray