Save address with Utxo.

We want only one utxo file per wallet, so each serialized Utxo needs
to also contain the receiving address.

tx/tx.go

@@ -43,6 +43,7 @@ type UtxoStore struct {
 }
 
 type Utxo struct {
+	Addr   [ripemd160.Size]byte
 	TxHash btcwire.ShaHash
 	Amt    int64 // Measured in Satoshis
 	Height int64
@@ -180,6 +181,7 @@ func (u *UtxoStore) WriteTo(w io.Writer) (n int64, err error) {
 // Each field is read little endian.
 func (u *Utxo) ReadFrom(r io.Reader) (n int64, err error) {
 	datas := []interface{}{
+		&u.Addr,
 		&u.TxHash,
 		&u.Amt,
 		&u.Height,
@@ -203,6 +205,7 @@ func (u *Utxo) ReadFrom(r io.Reader) (n int64, err error) {
 // Each field is written little endian.
 func (u *Utxo) WriteTo(w io.Writer) (n int64, err error) {
 	datas := []interface{}{
+		&u.Addr,
 		&u.TxHash,
 		&u.Amt,
 		&u.Height,

tx/tx_test.go

@@ -87,6 +87,10 @@ var (
 
 func TestUtxoWriteRead(t *testing.T) {
 	utxo1 := &Utxo{
+		Addr: [ripemd160.Size]byte{
+			0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+			16, 17, 18, 19,
+		},
 		TxHash: [btcwire.HashSize]byte{
 			0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
 			16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,