message: remove warnings in the utxo module
diff: -use cardano::{coin::{Coin}, tx::{TxIn, TxId, TxOut}, address::{ExtendedAddr}, bip::bip44, hdpayload};
  +use cardano::{coin::{Coin}, tx::{TxIn, TxId, TxOut}, address::{ExtendedAddr}};
  use std::{fmt, collections::{BTreeMap}};
  use super::ptr::{StatePtr};
  @@ -91,18 +91,3 @@ impl<A: fmt::Display> fmt::Display for UTxO<A> {
  /// collections for quick lookup of `UTxO` by `TxId`
  pub type UTxOs<A> = BTreeMap<TxIn, UTxO<A>>;
  -
  -/// iterator over the blockchain, constructing the UTxO on the fly
  -/// for consumption by other operators
  -///
  -pub struct UTxOIterator<A>(::std::marker::PhantomData<A>); // TODO
  -
  -pub type AnonymousUtxoIterator = UTxOIterator<ExtendedAddr>;
  -pub type BIP44UtxoIterator = UTxOIterator<bip44::Addressing>;
  -pub type WithPayloadUtxoIterator = UTxOIterator<hdpayload::Path>;
  -
  -impl<A> Iterator for UTxOIterator<A> {
  - type Item = UTxO<A>;
  - // TODO
  - fn next(&mut self) -> Option<Self::Item> { None }
  -}
  