Merge pull request 'WIP Finir interface Manager' (#37) from creer_interface_manager into main

Reviewed-on: #37

Sources/Model/IManager.cs

@@ -8,6 +8,8 @@ namespace Model
 {
     internal interface IManager
     {
-
+        public T Add<T>(ref T toAdd);
+        public T Remove<T>(ref T toRemove);
+        public T Update<T>(ref T before, ref T after);
     }
 }