Refactor the runtime API to use traits. (#878)

* Add missing `As` imports.

* Adds new API traits that will be used by the client and runtime

* Switch consensus to new API's

* Switches transaction-pool to new API's

* Move runtime api stuff into its own crate

* Adds `impl_apis!` macro for implementing the new API traits

* Make `metadata` return directly a blob

* Runtime replace `impl_stubs!` with `impl_apis!`

* Switches to none feature based approach for declaring the different API traits

* Fixes compilation error

* Fixes errors

* Make the `decl_apis!` trait usable from the outside

* Make the `test-client` use the new API traits

* Remove last `impl_stubs!` bits and move some of them into wasm executor for tests

* A little bit more documentation

substrate/core/sr-primitives/Cargo.toml

@@ -13,6 +13,7 @@ parity-codec-derive = { version = "2.0", default-features = false }
 substrate-primitives = { path = "../primitives", default-features = false }
 sr-std = { path = "../sr-std", default-features = false }
 sr-io = { path = "../sr-io", default-features = false }
+sr-version = { path = "../sr-version", default-features = false }
 log = {version = "0.4", optional = true }
 
 [dev-dependencies]
@@ -27,6 +28,8 @@ std = [
 	"log",
 	"sr-std/std",
 	"sr-io/std",
+	"sr-version/std",
 	"parity-codec/std",
 	"substrate-primitives/std",
 ]
+api-for-runtime = []

substrate/core/sr-primitives/src/lib.rs

@@ -37,6 +37,7 @@ extern crate num_traits;
 extern crate integer_sqrt;
 extern crate sr_std as rstd;
 extern crate sr_io as runtime_io;
+extern crate sr_version as runtime_version;
 #[doc(hidden)]
 pub extern crate parity_codec as codec;
 extern crate substrate_primitives;