Integrate transaction pool to the proposal logic (#80)

* reshuffle consensus libraries

* polkadot-useful type definitions for statement table

* begin BftService

* primary selection logic

* bft service implementation without I/O

* extract out `BlockImport` trait

* allow bft primitives to compile on wasm

* Block builder (substrate)

* take polkadot-consensus down to the core.

* test for preemption

* fix test build

* Fix wasm build

* Bulid on any block

* Test for block builder.

* Block import tests for client.

* Tidy ups

* clean up block builder instantiation

* justification verification logic

* JustifiedHeader and import

* Propert block generation for tests

* network and tablerouter trait

* use statement import to drive creation of further statements

* Fixed rpc tests

* custom error type for consensus

* create proposer

* asynchronous proposal evaluation

* inherent transactions in polkadot runtime

* fix tests to match real polkadot block constraints

* implicitly generate inherent functions

* add inherent transaction functionality to block body

* block builder logic for polkadot

* some tests for the polkadot API

* avoid redundancy in native code compatibility check

* helper for extracting nonce

* transaction pool implementation

* transaction pool

* integrate transaction pool with proposer

* indentation

* kill storage keys module

* accept new transactions to replace old

substrate/polkadot/runtime/src/api.rs

@@ -14,7 +14,7 @@
 // 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, timestamp};
+use runtime::{system, parachains, consensus, session};
 
 impl_stubs!(
 	execute_block => |block| system::internal::execute_block(block),
@@ -24,5 +24,6 @@ impl_stubs!(
 	validators => |()| session::validators(),
 	authorities => |()| consensus::authorities(),
 	duty_roster => |()| parachains::calculate_duty_roster(),
-	get_timestamp => |()| timestamp::get()
+	timestamp => |()| ::runtime::timestamp::get(),
+	nonce => |account_id| system::nonce(account_id)
 );