Merge branch 'master' of https://github.com/paritytech/parity into warp_sync_on_light_client

* 'master' of https://github.com/paritytech/parity:
  Allow setting the panic hook with parity-clib (#9292)
  Prevent blockchain & miner racing when accessing pending block. (#9310)
  Docker alpine: use multi-stage concept (#9269)
  Update `log` -> 0.4, `env_logger` -> 0.5. (#9294)
  Update tobalaba.json (#9313)
  Allow tx pool to be Send (#9315)
  Fix codecov.io badge in README (#9327)
  Move ethereum-specific H256FastMap type to own crate (#9307)
  ethcore sync decodes rlp less often (#9264)