start implementation of magazine

Magazine.cs

@@ -0,0 +1,21 @@
+namespace Bücherwurm
+{
+    public class Magazine : IProduct
+    {
+        public int ProductId {get; set;}
+
+        public string ImageLink {get; set;}
+
+        public string Category {get; set;}
+
+        public int LendTime {get; set;}
+
+        public void OverwriteNullId(int Id)
+        {
+            if (ProductId == 0)
+            {
+                ProductId = Id;
+            }
+        }
+    }
+}