update todo

pd/nw/todo.txt

@@ -281,7 +281,7 @@ Everything else: (A [x] means we've fixed it)
 [x] 60e06b3155458b561f3fb1ace17874eac9c5592a
     Hunks failed.  Patch manually.
 [ ] same for all commits up to Jul 31, 2015
-[ ] address double-free when closing a canvas that is a canvas field
+[x] address double-free when closing a canvas that is a canvas field
     of a scalar
 [ ] current try/catch parser in the socket receiver is too slow. For lots of
     data it can end up freezing the GUI. (Test if requestAnimationFrame makes