import/export accounts

- cli: add passwordfile flag
- cli: change unlock flag only takes account
- cli: with unlock you are prompted for password or use passfile with password flag
- cli: unlockAccount used in normal client start (run) and accountExport
- cli: getPassword used in accountCreate and accountImport
- accounts: Manager.Import, Manager.Export
- crypto: SaveECDSA (to complement LoadECDSA) to save to file
- crypto: NewKeyFromECDSA added (used in accountImport and New = generated constructor)

crypto/key.go

@@ -85,6 +85,16 @@ func (k *Key) UnmarshalJSON(j []byte) (err error) {
 	return err
 }
 
+func NewKeyFromECDSA(privateKeyECDSA *ecdsa.PrivateKey) *Key {
+	id := uuid.NewRandom()
+	key := &Key{
+		Id:         id,
+		Address:    PubkeyToAddress(privateKeyECDSA.PublicKey),
+		PrivateKey: privateKeyECDSA,
+	}
+	return key
+}
+
 func NewKey(rand io.Reader) *Key {
 	randBytes := make([]byte, 64)
 	_, err := rand.Read(randBytes)
@@ -97,11 +107,5 @@ func NewKey(rand io.Reader) *Key {
 		panic("key generation: ecdsa.GenerateKey failed: " + err.Error())
 	}
 
-	id := uuid.NewRandom()
-	key := &Key{
-		Id:         id,
-		Address:    PubkeyToAddress(privateKeyECDSA.PublicKey),
-		PrivateKey: privateKeyECDSA,
-	}
-	return key
+	return NewKeyFromECDSA(privateKeyECDSA)
 }