Merge branch 'refactor/substrate-state-machine-generic' of github.com:paritytech/polkadot into refactor/substrate-state-machine-generic

* 'refactor/substrate-state-machine-generic' of github.com:paritytech/polkadot:
  Update Cargo.lock
  Remove safe-mix (#521)

* master:
  README: fixed typo in docker run command (#518)
  Merge *_at methods. (#515)
  New flags to listen to all interfaces (#495)
  If contract reaches max depth, return Err (#503)
  Some networking cleanups (#504)
  Derivable Encode & Decode (#509)
  substrate: return Option in all storage related RPC methods (#510)
  Build with locked Cargo.lock on CI (#514)
  Place call data into a newly allocated pages (#502)

* Add new flag to allow listening to all interfaces

Fix #439
Fix #494

* Fix capitalisation

* Some networking cleanups

* Fix tests

* Fix wrong port in new_local

* Derive macro for simple structs.

* Derive Encode/Decode wherever we can.

* Derive for enums.

* Support discriminant.

* Get rid of some repetition.

* Support custom indices.

* Derive codec for enums wherever possible.

* Fix no_std

* WASM rebuilt

* Avoid excessive import.

* Fix compilation.

* Address review grumbles.

* substrate: return Option in all storage related RPC methods

* substrate: remove unused imports

* substrate: remove unused NoValueForKey error variant

* substrate: don't return Option on code_at since code is always defined

* master:
  Fix some formatting grumbles (#501)
  remove the extra ? in the license header (#500)
  NetworkService::new starts the network (#462)
  Availability/Extrinsic store (#465)
  Add doc to install a specific tagged version (#497)

Use core