Snapshot synchronization

[remagpie]

https://github.com/CodeChain-io/codechain/blob/master/spec/Block-Synchronization-Extension.md

Depends on: #1884

Todo:

• Generate snapshots periodically (10/31~)
  • Compress/decompress chunk
  • Make a state into chunks
  • Read & verify chunks and recover the state
  • Make chunk snapshot and recover property test success Chunk based snapshot & restore #1844 (~11/13)
  • Add block event listener to snapshot periodically (~11/15) Periodic snapshot #1869
    • for the tendermint (~11/19) Tendermint periodic snapshot #1874
  • Snapshot configurations
    • Set the expiration date Add autoremoving expired snapshot feature #1875
• Update the sync extension for snapshot sync
  • Update network messages for snapshots (~11/14) Update snapshot message format #1843
  • Switch to full sync after the snapshot sync is finished Add state to sync extension #1855 (~11/15)
  • Make snapshot header importable
    • Make consensus extensions to work without parent header (~11/27) (@remagpie)
    • Make blockchain work without history (~11/15) Fetch snapshot header from peers #1862
    • Update sync extension to ignore total_score of status message (~11/19) Rename total_score to nonce in sync message #1864
  • Fetch snapshot header from peers (~11/15) Fetch snapshot header from peers #1862
  • Collect snapshots from peers (~11/22) Collect snapshot chunks from peers #1872
• RPC to query the snapshot information (~11/22) Add RPC snapshot_getList #1873
• Test functionallity on testnet (~12/1)

Good To Have:

• Make the snapshot period configurable