More cleanups of custom classes in favor of .NET runtime types.

Source/Game/Entities/Unit/Unit.Fields.cs

@@ -17,13 +17,10 @@
 
 using Framework.Collections;
 using Framework.Constants;
-using Framework.Dynamic;
 using Game.AI;
 using Game.Combat;
 using Game.DataStorage;
-using Game.Maps;
 using Game.Movement;
-using Game.Networking;
 using Game.Networking.Packets;
 using Game.Spells;
 using System;