Cleanup & Fixes for .NET 5 (#309)

- [X] Fixes several bugs
- [X] Updates more ordinal issues
- [X] Cleans up the code a bit
- [X] Turns classes static that should have been
- [X] Changes TcpServer.Instances to a HashSet

Bumps release version

Projects/Server/Main.cs

@@ -61,7 +61,9 @@ namespace Server
         public static bool IsRunningFromXUnit =>
             m_IsRunningFromXUnit ??= AppDomain.CurrentDomain.GetAssemblies()
                 .Any(
-                    a => a.FullName?.ToLowerInvariant().StartsWith("xunit") ?? false
+                    a => a.FullName?
+                        .ToUpperInvariant()
+                        .StartsWith("XUNIT", StringComparison.Ordinal) ?? false
                 );
 
         public static bool Profiling