Make API backwards compatible with CC (#1697)

* Rework how a runtime api calls into the runtime

Now we generate a default implementation for each api call that calls
a generated method `method_runtime_api_impl`. This newly generated
method is the one that will be implemented by the `impl_runtime_apis`
macro in the runtime for the client side.

* Support `changed_in` to change runtime api function signatures

* Update documentation

* Fixes tests

* Implement checking the api version with a predicate

* Make the implementation backwards compatible with CC

* Update wasm files after merge

* Check for wasm runtime differences by building master and current branch

* Update spec_version and wasm files

* Fixes

* Revert my changes

* Remove `patch.crates-io` from test-runtime

substrate/core/basic-authorship/src/basic_authorship.rs

@@ -96,10 +96,10 @@ impl<B, E, Block, RA> AuthoringApi for SubstrateClient<B, E, Block, RA> where
 		let mut block_builder = self.new_block_at(at)?;
 
 		let runtime_api = self.runtime_api();
-		if runtime_api.has_api::<BlockBuilderApi<Block>>(at)? {
-			runtime_api.inherent_extrinsics(at, inherent_data)?
-				.into_iter().try_for_each(|i| block_builder.push(i))?;
-		}
+		// We don't check the API versions any further here since the dispatch compatibility
+		// check should be enough.
+		runtime_api.inherent_extrinsics(at, inherent_data)?
+			.into_iter().try_for_each(|i| block_builder.push(i))?;
 
 		build_ctx(&mut block_builder);