Re-introduce zero copy codec and add minimal polkadot client API which uses linked native runtime (#65)

* client-api type and move duty roster types to primitives

* tuple implementation for slicable

* mild cleanup of deserialization code

* stubs which handle encoding and decoding themselves

* fancier impl_stubs macro

* zero-copy slicable API

* minimal polkadot-client API

* fix WASM API generation

* move native environment stuff to substrate executor

* fix warnings and grumbles

substrate/polkadot/runtime/src/api.rs

@@ -0,0 +1,27 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use runtime::{system, parachains, consensus, session};
+
+impl_stubs!(
+	execute_block => |block| system::internal::execute_block(block),
+	execute_transaction => |(header, utx)| system::internal::execute_transaction(utx, header),
+	finalise_block => |header| system::internal::finalise_block(header),
+	validator_count => |()| session::validator_count(),
+	validators => |()| session::validators(),
+	authorities => |()| consensus::authorities(),
+	duty_roster => |()| parachains::calculate_duty_roster()
+);