Apply R# clean-up for reliability (#877)

* 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

VocaluxeLib/Menu/IMenu.cs

@@ -19,7 +19,7 @@ namespace VocaluxeLib.Menu
 {
     public interface IMenu
     {
-        int PartyModeID { get; }
+        int PartyModeId { get; }
 
         void Init();