Implement runtime version checks in set_code (#4548)

* Implement runtime version checks in `set_code`

Check that the new runtime code given to `set_code` fullfills some
requirements:

- `spec_name` matches
- `spec_version` does not decreases
- `impl_version` does not decreases
- Either `spec_version` and `impl_version` increase

* Make tests almost work

* Some fixes after master merge

* Fix tests

* Add missed file

* Make depedency check happy?

* Remove leftover `sc-executor`

* AHHHHH

* Reset debug stuff

* Remove some 'static

* More 'static

* Some docs

* Update `Cargo.lock`

substrate/client/src/light/fetcher.rs

@@ -197,7 +197,7 @@ impl<E, H, B: BlockT, S: BlockchainStorage<B>> LightDataChecker<E, H, B, S> {
 impl<E, Block, H, S> FetchChecker<Block> for LightDataChecker<E, H, Block, S>
 	where
 		Block: BlockT,
-		E: CodeExecutor,
+		E: CodeExecutor + Clone + 'static,
 		H: Hasher,
 		H::Out: Ord + codec::Codec + 'static,
 		S: BlockchainStorage<Block>,