Extrinsic pool (#182)

* Use latest version of txpool.

* Initial version of the pool.

* Fix abstraction.

* Implement watchers and notifications.

* Return hash from RPC.

* Remove commented code.

* Remove client dep.

* Fix tests.

substrate/Cargo.toml

@@ -22,22 +22,22 @@ members = [
 	"polkadot/parachain",
 	"polkadot/primitives",
 	"polkadot/runtime",
+	"polkadot/service",
 	"polkadot/statement-table",
 	"polkadot/transaction-pool",
-	"polkadot/service",
-
 	"substrate/bft",
 	"substrate/client",
 	"substrate/client/db",
 	"substrate/codec",
 	"substrate/environmental",
 	"substrate/executor",
+	"substrate/extrinsic-pool",
 	"substrate/keyring",
-	"substrate/network",
 	"substrate/misbehavior-check",
+	"substrate/network",
 	"substrate/primitives",
-	"substrate/rpc-servers",
 	"substrate/rpc",
+	"substrate/rpc-servers",
 	"substrate/runtime-io",
 	"substrate/runtime-sandbox",
 	"substrate/runtime-std",
@@ -55,10 +55,10 @@ members = [
 	"substrate/state-machine",
 	"substrate/test-runtime",
 
-	"demo/runtime",
-	"demo/primitives",
-	"demo/executor",
 	"demo/cli",
+	"demo/executor",
+	"demo/primitives",
+	"demo/runtime",
 	"safe-mix",
 	"subkey",
 ]