message: Add ToBytes impl for &T
diff: @@ -1201,6 +1201,19 @@ impl ToBytes for &str {
  }
  }
  +impl<T> ToBytes for &T
  +where
  + T: ToBytes,
  +{
  + fn to_bytes(&self) -> Result<Vec<u8>, Error> {
  + (*self).to_bytes()
  + }
  +
  + fn serialized_length(&self) -> usize {
  + (*self).serialized_length()
  + }
  +}
  +
  impl<T> ToBytes for Ratio<T>
  where
  T: Clone + Integer + ToBytes,
  