Rialto to Millau Transfer Generator (#568)

* Add option to relay for sending transfers to Millau chain

* Endow derived accounts on Millau chain

* Update message generator entrypoint script to send transfers

* Use correct command when sending messages

* Send Root messages from Root origin on source chain

* Wrap calls from Root Origin in Sudo Call

* Allow Root to send messages without paying fees

* Use correct variable when sending messages to Rialto

* Print warning if no message type is provided to script.

* Add note mentioning that certain source origins aren't supported yet

* Use correct runtime when initializing header sync

* Remove option to send messages as Root

* Remove endowment of derived Root accounts

* Fix indentation.

Co-authored-by: Tomasz Drwięga <tomasz@parity.io>

bridges/relays/substrate/src/cli.rs

@@ -138,12 +138,15 @@ pub enum Command {
 		/// Hex-encoded lane id.
 		#[structopt(long)]
 		lane: HexLaneId,
-		/// Message type.
-		#[structopt(long, possible_values = &ToMillauMessage::variants())]
-		message: ToMillauMessage,
 		/// Delivery and dispatch fee.
 		#[structopt(long)]
 		fee: bp_rialto::Balance,
+		/// Message type.
+		#[structopt(subcommand)]
+		message: ToMillauMessage,
+		/// The origin to use when dispatching the message on the target chain.
+		#[structopt(long, possible_values = &Origins::variants())]
+		origin: Origins,
 	},
 }
 
@@ -161,19 +164,24 @@ pub enum ToRialtoMessage {
 	},
 }
 
-arg_enum! {
-	#[derive(Debug)]
-	/// All possible messages that may be delivered to the Millau chain.
-	pub enum ToMillauMessage {
-		Remark,
-	}
+/// All possible messages that may be delivered to the Millau chain.
+#[derive(StructOpt, Debug)]
+pub enum ToMillauMessage {
+	/// Make an on-chain remark (comment).
+	Remark,
+	/// Transfer the specified `amount` of native tokens to a particular `recipient`.
+	Transfer {
+		#[structopt(long)]
+		recipient: bp_millau::AccountId,
+		#[structopt(long)]
+		amount: bp_millau::Balance,
+	},
 }
 
 arg_enum! {
 	#[derive(Debug)]
 	/// The origin to use when dispatching the message on the target chain.
 	pub enum Origins {
-		Root,
 		Target,
 		Source,
 	}