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

PartyModes/PartyModeChallenge/CPartyScreenChallengeSongs.cs

@@ -1,8 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using VocaluxeLib.Menu;
+using VocaluxeLib.Menu;
 
 namespace VocaluxeLib.PartyModes.Challenge
 {
@@ -26,7 +22,7 @@ namespace VocaluxeLib.PartyModes.Challenge
             Source = _PartyMode.GameData.SongSource;
             Sorting = _PartyMode.GameData.Sorting;
             Category = _PartyMode.GameData.CategoryIndex;
-            Playlist = _PartyMode.GameData.PlaylistID;
+            Playlist = _PartyMode.GameData.PlaylistId;
             SongMode = _PartyMode.GameData.GameMode;
             NumMedleySongs = _PartyMode.GameData.NumMedleySongs;
 
@@ -62,9 +58,9 @@ namespace VocaluxeLib.PartyModes.Challenge
             _PartyMode.GameData.SongSource = Source;
             _PartyMode.GameData.Sorting = Sorting;
             _PartyMode.GameData.CategoryIndex = Category;
-            _PartyMode.GameData.PlaylistID = Playlist;
+            _PartyMode.GameData.PlaylistId = Playlist;
             _PartyMode.GameData.GameMode = SongMode;
             _PartyMode.GameData.NumMedleySongs = NumMedleySongs;
         }
     }
-}
+}