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/Commands/Generic/Implementors/BaseCommandImplementor.cs

@@ -194,7 +194,7 @@ namespace Server.Commands.Generic
                     sb.Append(' ');
                 }
 
-                if (args[i].IndexOf(' ') >= 0)
+                if (args[i].Contains(' ', StringComparison.Ordinal))
                 {
                     sb.Append('"');
                     sb.Append(args[i]);