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/Mobiles/MovementRecord.cs

@@ -20,7 +20,7 @@ namespace Server.Mobiles
     public class MovementRecord
     {
         private static readonly Queue<MovementRecord> m_InstancePool = new Queue<MovementRecord>();
-        public long m_End;
+        private long m_End;
 
         private MovementRecord(long end) => m_End = end;