cmd/litcli: add payment flags back

Some flags that didn't make sense were removed when cleaning up the
keysend usecase, but some of them are still useful and we add them back.

cmd/litcli/ln.go

@@ -374,6 +374,18 @@ var sendPaymentCommand = cli.Command{
 			Name:  "force, f",
 			Usage: "will skip payment request confirmation",
 		},
+		cli.BoolFlag{
+			Name:  "allow_self_payment",
+			Usage: "allow sending a circular payment to self",
+		},
+		cli.StringFlag{
+			Name: "data",
+			Usage: "attach custom data to the payment. The " +
+				"required format is: <record_id>=<hex_value>," +
+				"<record_id>=<hex_value>,.. For example: " +
+				"--data 3438382=0a21ff. Custom record ids " +
+				"start from 65536.",
+		},
 		cli.UintFlag{
 			Name: "max_parts",
 			Usage: "the maximum number of partial payments that " +