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/ObjectPropertyList.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 using System.Text;
 using Server.Network;
@@ -99,7 +100,7 @@ namespace Server
             }
 
             AddHash(number);
-            AddHash(arguments.GetHashCode());
+            AddHash(arguments.GetHashCode(StringComparison.Ordinal));
 
             Stream.Write(number);