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/UOContent/Accounting/Account.cs

@@ -775,7 +775,7 @@ namespace Server.Accounting
             }
 
             m_PasswordAlgorithm = algorithm;
-            Password = password?.Replace("-", string.Empty);
+            Password = password.Replace("-", string.Empty, StringComparison.Ordinal);
             return true;
         }