Make runtime api generate version and identifier information (#1226)

* Make `decl_runtime_apis!` implement `RuntimeApiInfo` for all runtime
apis

* Make the runtime side generate the info constants as well

* Make `RuntimeApiInfo` implementation use the correct generics

* Adds a test for the runtime api info stuff

* Remove duplicated code by using block from `test-client`

* Adds `compile_fail` tests for `api_version`

* Adds documentation for `api_version`

* Make `impl_runtime_apis!` generate `RUNTIME_API_VERSIONS`

* Update documentation and tests for `RUNTIME_API_VERSIONS`

* Implement `has_api` by using the `RuntimeApiInfo`

* Make `impl_runtime_apis` check that trait identifiers are unique

* Prefix all runtime api function with the corresponding trait

So `execute_block` will be called `Core_execute_block`.
This makes it possible to have traits implement a function with the
same name.

* Rebase master

* Update after master rebase

substrate/node/runtime/wasm/Cargo.lock

@@ -827,8 +827,8 @@ name = "serde_derive"
 version = "1.0.79"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.15.22 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -900,8 +900,9 @@ dependencies = [
 name = "sr-api-macros"
 version = "0.1.0"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.15.22 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1164,6 +1165,7 @@ version = "0.1.0"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sr-api-macros 0.1.0",
  "srml-support-procedural-tools 0.1.0",
  "syn 0.15.22 (registry+https://github.com/rust-lang/crates.io-index)",
 ]