message: add serde Serialize and Deserialize instances
diff: use hdpayload::{Path};
  -//const BIP44_PATH_LENGTH: usize = 5;
  const BIP44_PURPOSE : u32 = 0x8000002C;
  const BIP44_COIN_TYPE : u32 = 0x80000717;
  -#[derive(Clone)]
  +#[derive(Clone, Serialize, Deserialize, Debug, PartialEq, Eq)]
  pub struct Addressing {
  account: u32,
  change: u32,
  index: u32,
  }
  +#[derive(Clone, Serialize, Deserialize, Debug, PartialEq, Eq)]
  pub enum AddrType {
  Internal,
  External,
  