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/Gumps/Gump.cs

@@ -55,7 +55,7 @@ namespace Server.Gumps
 
         public bool Closable { get; set; } = true;
 
-        public static int GetTypeID(Type type) => type?.FullName?.GetHashCode() ?? -1;
+        public static int GetTypeID(Type type) => type?.FullName?.GetHashCode(StringComparison.Ordinal) ?? -1;
 
         public void AddPage(int page)
         {