message: add Display instance for AddrType
diff: @@ -76,6 +76,15 @@ pub enum AddrType {
  ATScript,
  ATRedeem
  }
  +impl fmt::Display for AddrType {
  + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  + match self {
  + AddrType::ATPubKey => write!(f, "Public Key"),
  + AddrType::ATScript => write!(f, "Script"),
  + AddrType::ATRedeem => write!(f, "Redeem"),
  + }
  + }
  +}
  // [TkListLen 1, TkInt (fromEnum t)]
  impl AddrType {
  fn from_u64(v: u64) -> Option<Self> {
  