83512d2 [Trivial] Mark CCoinsView child classes methods as override (random-zebra)
5643075 Store/allow tx metadata in all undo records (random-zebra)
8c4add4 Report on-disk size in gettxoutsetinfo (random-zebra)
6cb2989 Remove/ignore tx version in utxo and undo (random-zebra)
03b9724 Add specialization of SipHash for 256 + 32 bit data (Pieter Wuille)
e3cd496 Introduce CHashVerifier to hash read data (random-zebra)
10baa70 error() in disconnect for disk corruption, not inconsistency (random-zebra)
802f8c8 Add SizeEstimate to CDBBatch (Pieter Wuille)

Pull request description:

  This backports the commits listed as "Preparation" in bitcoin#10195.
  The rest will be included in a followup PR.

  Built on top of:
  - [x] #1772
  - [x] #1771
  - [x] #1793

  Here we:
  - add in-memory size estimation of a LevelDB batch
  - remove the usage of `error()` in ApplyTxInUndo/DisconnectBlock
  - Introduce the new CHashVerifier class to hash read data
  - Add a specialized version of SipHash for tuples of 256 bits and 32 bits data
  - Remove the transaction version from utxo and undo data structures
  - Add on-disk size of the utxo set to gettxoutsetinfo
  - store tx metadata in all undo records, instead of records corresponding only to the last output of a tx being spent.

ACKs for top commit:
  furszy:
    looking good, utACK 83512d2.
  Fuzzbawls:
    utACK 83512d2

Tree-SHA512: 7db730058ae208535aad5f5989abb9c55fd3722b79efef24fdd8c717687b67272bddaeae5e5a4a2d3e97626a7ec62a5d1ebdb5af0233f4a950b5a0c0b154484f