message: add WIP Utxo representation
diff: use std::result;
  use std::collections::{BTreeMap, VecDeque};
  -use blockchain::{Block, BlockDate, HeaderHash};
  +use blockchain::{Block, BlockDate, HeaderHash, SlotId};
  use wallet_crypto::bip44;
  use wallet_crypto::hdwallet;
  use wallet_crypto::hdpayload;
  use wallet_crypto::address::ExtendedAddr;
  -use wallet_crypto::tx::TxOut;
  +use wallet_crypto::tx::{TxId, TxOut};
  +use wallet_crypto::coin::Coin;
  #[derive(Debug)]
  pub enum Error {
  @@ -141,6 +142,16 @@ fn is_our_ri_address(key: &hdpayload::HDKey, addr: &ExtendedAddr) -> bool {
  }
  }
  +#[derive(Clone,Debug)]
  +pub struct Utxo {
  + block_addr: SlotId,
  + wallet_addr: bip44::Addressing,
  + txid: TxId,
  + coin: Coin,
  +}
  +
  +type Utxos = Vec<Utxo>;
  +
  #[derive(Clone,Debug)]
  pub struct StateAccount<T: AddrLookup> {
  lookup_struct: T,
  