Box<T> unsupported

[io12]

If the type being serialized has fields containing Box<T>, the field's expression is assigned to the inner value, not wrapped in Box::new(), which causes a compiler error.

[burdges]

As in #2 serde causes this by applying Deref fully. It's doable with post-processing, but really one wants some new formatter traits, similar to Debug and Display, and just avoid serde entirely.