message: chore: CHANGELOG for v0.20.0
diff: -# [v0.19.0](https://github.com/nervosnetwork/ckb/compare/v0.18.2...v0.19.9) (2019-08-24)
  +# [v0.20.0](https://github.com/nervosnetwork/ckb/compare/v0.19.2...v0.20.0) (2019-09-07)
  +
  +### Features
  +
  +* #1464: Use secp256k1 referenced by hash type "type" as the default lock. (@doitian)
  +* #1505: Refactor serialization schema for performance. (@doitian)
  +* #1508: Add `load_header_by_field` syscall for fetching epoch data (@xxuejie)
  +* #1469: Change `Header#dao` to Byte32 (@quake)
  +
  +### Bug Fixes
  +
  +* #1393: Use path-clean (@zjhmale)
  +* #1463: Change default lock script (@TheWaWaR)
  +* #1413: Use remote peer observed address (@jjyr)
  +
  + Observe address is a feature to leverage remote peers to report external IPs for a node.
  +
  +* #1487: Fix dao statistics in genesis block (@TheWaWaR)
  +* #1519: Indexer store should lock the state when syncing data (@quake)
  +* #1548: Consensus constructor should init epoch reward from parameter. (@doitian)
  +* #1555: Fix orphan block race storage (@keroro520)
  +* #1562: Block serialized size should not include uncles proposals serialized size (@yangby-cryptape)
  +
  +### Improvements
  +
  +* #1352: Conduct GCD before rational ops (@u2)
  +* #1486: Use Byte32 to replace the majority of H256 (@yangby-cryptape)
  +* #1520: Resolve indexer store performance issue (@quake)
  +
  +# [v0.19.2](https://github.com/nervosnetwork/ckb/compare/v0.18.2...v0.19.2) (2019-08-24)
  ### Features
  