message: extend feature of the bip44::Addressing to retrieve the addr type
diff: @@ -19,8 +19,8 @@ pub enum AddrType {
  impl Addressing {
  pub fn new(account: u32, typ: AddrType) -> Self {
  let change = match typ {
  - AddrType::Internal => 0,
  - AddrType::External => 1,
  + AddrType::Internal => 1,
  + AddrType::External => 0,
  };
  Addressing { account: 0x80000000 | account, change: change, index: 0 }
  }
  @@ -29,6 +29,14 @@ impl Addressing {
  Path::new(vec![BIP44_PURPOSE, BIP44_COIN_TYPE, self.account, self.change, self.index])
  }
  + pub fn address_type(&self) -> AddrType {
  + if self.change == 0 {
  + AddrType::External
  + } else {
  + AddrType::Internal
  + }
  + }
  +
  pub fn from_path(path: Path) -> Option<Self> {
  if path.as_ref().len() != 5 { return None; }
  if path.as_ref()[0] != BIP44_PURPOSE { return None; }
  