Downward & Upward messages (#1266)

* Downward messages, the front-end.

* Move types around to make them accessible from Parachains

* Fix compilation

* Fix branch

* Make it compile for Cumulus

* Update the branch names

* Add default generic parameter

* Implement `Partialeq`

* Move upward messages into the `ValidationResult`

* Support disabling of the runtime api

* Update branch

* Adds support for handling downward messages

* Implement sending XCMP messages as up/downward messages

* service: update to latest ServiceBuilder changes

* Make it compile

* Initial commit

Forked at: ef2aa428d7
Parent branch: origin/master

* Update substrate branch to cecton-update-polkadot-substrate

* Update substrate & polkadot to cumulus-branch

* Reset branch

* Update primitives/src/parachain.rs

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Update runtime/common/src/parachains.rs

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Update runtime/common/src/parachains.rs

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Minor fixes

* Fix wasm build

Co-authored-by: Gav Wood <gavin@parity.io>
Co-authored-by: André Silva <andre.beat@gmail.com>
Co-authored-by: Cecile Tonglet <cecile.tonglet@cecton.com>
Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

polkadot/parachain/test-parachains/tests/adder/mod.rs

@@ -16,15 +16,11 @@
 
 //! Basic parachain that adds a number as part of its state.
 
-use crate::{
-	DummyExt,
-	parachain,
-	parachain::primitives::{
-		RelayChainBlockNumber,
-		BlockData as GenericBlockData,
-		HeadData as GenericHeadData,
-		ValidationParams,
-	},
+use parachain::primitives::{
+	RelayChainBlockNumber,
+	BlockData as GenericBlockData,
+	HeadData as GenericHeadData,
+	ValidationParams,
 };
 use codec::{Decode, Encode};
 
@@ -83,7 +79,6 @@ pub fn execute_good_on_parent() {
 			relay_chain_height: 1,
 			code_upgrade_allowed: None,
 		},
-		DummyExt,
 		parachain::wasm_executor::ExecutionMode::RemoteTest(&pool),
 	).unwrap();
 
@@ -123,7 +118,6 @@ fn execute_good_chain_on_parent() {
 				relay_chain_height: number as RelayChainBlockNumber + 1,
 				code_upgrade_allowed: None,
 			},
-			DummyExt,
 			parachain::wasm_executor::ExecutionMode::RemoteTest(&pool),
 		).unwrap();
 
@@ -164,7 +158,6 @@ fn execute_bad_on_parent() {
 			relay_chain_height: 1,
 			code_upgrade_allowed: None,
 		},
-		DummyExt,
 		parachain::wasm_executor::ExecutionMode::RemoteTest(&pool),
 	).unwrap_err();
 }