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)

cmd/utils/flags.go

@@ -104,7 +104,13 @@ var (
 	}
 	UnlockedAccountFlag = cli.StringFlag{
 		Name:  "unlock",
-		Usage: "Unlock a given account untill this programs exits (address:password)",
+		Usage: "unlock the account given until this program exits (prompts for password).",
+		Value: "",
+	}
+	PasswordFileFlag = cli.StringFlag{
+		Name:  "password",
+		Usage: "Password used when saving a new account and unlocking an existing account. If you create a new account make sure you remember this password.",
+		Value: "",
 	}
 
 	// logging and debug settings