Merge pull request #10 from Katori/patch-1

Don't attempt to copy if Data is null

Source/Managed/ENet.cs

@@ -400,7 +400,10 @@ namespace ENet
         {
             if (destination == null)
                 throw new ArgumentNullException("destination");
-
+            if (Data == null)
+            {
+                return;
+            }
             Marshal.Copy(Data, destination, 0, Length);
         }
     }
@@ -1191,4 +1194,4 @@ namespace ENet
         [DllImport(nativeLibrary, CallingConvention = CallingConvention.Cdecl)]
         internal static extern void enet_peer_reset(IntPtr peer);
     }
-}
+}