No Encodable/Decodable implementation for type "char"

In libstd/serialize.rs, the following is missing:

``` rust
impl<S:Encoder> Encodable<S> for char {
    fn encode(&self, s: &S) { s.emit_char(*self) }
}

impl<D:Decoder> Decodable<D> for char {
    fn decode(d: &D) ⟶  char {
        d.read_char()
    }
}
```
