message: Make Encoder cloneable
diff: @@ -173,7 +173,7 @@ impl<'a, 'b> PartialEq<Decoder<'b>> for Decoder<'a> {
  }
  /// Encoder is good for building data structures.
  -#[derive(Default, PartialEq)]
  +#[derive(Clone, Default, PartialEq)]
  pub struct Encoder {
  buf: Vec<u8>,
  }
  