Transaction factory (#2481)

* Fix typos

* Add transaction factory

`cargo run -- purge-chain -y --chain dev && cargo run -- --dev --transaction-factory 10`

* Fix comment and remove build deps

* Move crate to test-utils

* Switch from flag to subcommand

`cargo run -- factory --dev --num 5`

* Decouple factory from node specifics

* Introduce different manufacturing modes

* Remove unrelated changes

* Update Cargo.lock

* Use SelectChain to fetch best block

* Improve expect proof

* Panic if factory executed with unsupported chain spec

* Link ToDo comments to follow-up ticket

* Address comments and improve style

* Remove unused dependencies

* Fix indent level

* Replace naked unwrap

* Update node/cli/src/factory_impl.rs

* Fix typo

* Use inherent_extrinsics instead of timestamp

* Generalize factory and remove saturated conversions

* Format imports

* Make it clearer that database needs to be empty

* Ensure factory settings

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update test-utils/transaction-factory/src/lib.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Fix match guard syntax

* Simplify import, remove empty line

* Update node/cli/Cargo.toml

* Update lockfile

substrate/test-utils/transaction-factory/src/modes.rs

@@ -0,0 +1,41 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! The transaction factory can operate in different modes. See
+//! the `simple_mode` and `complex_mode` modules for details.
+
+use std::str::FromStr;
+
+/// Token distribution modes.
+#[derive(Debug, Clone, PartialEq)]
+pub enum Mode {
+	MasterToN,
+	MasterTo1,
+	MasterToNToM
+}
+
+impl FromStr for Mode {
+	type Err = String;
+	fn from_str(mode: &str) -> Result<Self, Self::Err> {
+		match mode {
+			"MasterToN" => Ok(Mode::MasterToN),
+			"MasterTo1" => Ok(Mode::MasterTo1),
+			"MasterToNToM" => Ok(Mode::MasterToNToM),
+			_ => Err(format!("Invalid mode: {}", mode)),
+		}
+	}
+}
+