message: chore: CHANGELOG for v0.31.0
diff: +# [v0.31.0](https://github.com/nervosnetwork/ckb/compare/v0.30.2...v0.31.0) (2020-04-02)
  +
  +### Sync Improvements
  +
  +* #1947: Repair using of snapshot (@zhangsoledad)
  +* #1959: Improve get_ancestor efficiency (@keroro520)
  +* #1957: Concurrent download blocks on ibd (@driftluo)
  +* #1966: Enhanced locator (@driftluo)
  +* #1961: Fix bug on last common marked (@driftluo)
  +* #1985: Speed up fetch collect (@driftluo)
  +* #1979: Fix build_skip performance bug (@TheWaWaR)
  +
  +### Features
  +
  +* #1954: Add detect-asm feature to script (@xxuejie)
  +* #1955: Bump CKB VM to fix a performance regression (@xxuejie)
  +* #1948: Use module disable error instead of method not found (@driftluo)
  +* #1956: Replace rocksdb wrapper (@zhangsoledad)
  +* #1946: Use same allocator for all (@yangby-cryptape)
  +* #1940: Add a feature to enable jemalloc profiling (@yangby-cryptape)
  +* #1881: Remove memory cellset (@zhangsoledad)
  +* #1923: Network upgrade to async (@driftluo)
  +* #1978: Built-in miner should support https RPC URL (@quake)
  +* #1958: Log more sync and relay metrics (@keroro520)
  +* #1992: Add an option to control how many blocks the miner has to mine (@yangby-cryptape)
  +
  + ```bash
  + ckb miner -C . --limit 10 # Exit after 10 nonces found
  + ckb miner -C . -l 5 # Exit after 5 nonces found
  + ckb miner -C . # Run forever
  + ckb miner -C . --limit 0 # Run forever, too
  + ```
  +
  +* #1993: Add metrics filter (@keroro520)
  +
  + Filter metrics via `log_enabled!` inside `metric!`.
  +
  +### Bug Fixes
  +
  +* #1977: Fix false positive in IllTransactionChecker (@xxuejie)
  +* #1996: Wait for RPC server to cleanup on shutdown (@zhangsoledad)
  +* #1997: Orphan_block_pool should record block origin (@zhangsoledad)
  +
  # [v0.30.2](https://github.com/nervosnetwork/ckb/compare/v0.30.1...v0.30.2) (2020-04-02)
  ### Bug Fixes
  