…tests

8152fee [Tests] Remove zerocoin prefix and v2 spends from spends test (random-zebra)
e0e8a35 [Tests] Remove wrapped_serials functional test (random-zebra)

Pull request description:

  There is no need to keep running these tests anymore.
  We can make Travis a bit faster.

ACKs for top commit:
  furszy:
    ACK 8152fee

Tree-SHA512: 03c179ea04cfbf67cccefaf5b0b2cb5d66253667e2f8c38106617223f1a00baa7a76ed6a2b5c4b01be9b7e84b73abca689b115a8480b377a47a65ec301096ea3

7a8d755 [Tests] Remove '-staking' from extra-args (random-zebra)
72d5a31 [Tests] Fix/Update mining_pos_coldstaking test (random-zebra)
5ffa6b5 [Trivial] Rename mintablecoins --> stakeablecoins (random-zebra)
e781cd0 [Cleanup] zPIV Don't validate Accumulator Checkpoints anymore (random-zebra)
5b192e0 [Tests][Bug] Fix staking status in generate_pos() (random-zebra)

Pull request description:

  This is based on top of #1276 and #1277 which should be reviewed before.
  `generate_pos` framework function relies on the output of `getstakingstatus` RPC which was recently changed.
  Since #1245, "validtime" is not returned anymore (nor it was ever really needed here).
  Only things that we need in `generate_pos` are "walletunlocked" and "mintablecoins" (renamed "stakeablecoins").
  "enoughcoins" is going to be removed in #1277 , and "haveconnections" is not required on regtest.
  This also updates coldstaking test.

ACKs for top commit:
  Fuzzbawls:
    ACK 7a8d755
  furszy:
    ACK 7a8d755

Tree-SHA512: 0f45d8b3880d8d88258861fc85c04e0c62a834cede8991e1370afcaef05a2fb714a4441e201d0bdfd89251628e92aa51496182b8088917a8f3a9b740a21272f6

799e3ad [Tests] Fix block version on RegTest (random-zebra)
00aae54 [Core][Cleanup] PoS: remove extra signature + IncrementExtraNonce (random-zebra)
389094f [Core] Remove StakeV1 in kernel and miner (random-zebra)

Pull request description:

  This removes the old StakeV1 function and does some minor optimizations in the miner code (removing redundant signature and IncrementExtraNonce calls).

  This is based on top of the following three pull requests and will be rebased after their merge into master.
  So, they should be reviewed before this one.
  - [x] #1276
  - [x] #1277
  - [x] #1278

ACKs for top commit:
  furszy:
    Staking working properly, ACK 799e3ad
  Fuzzbawls:
    ACK 799e3ad

Tree-SHA512: a3cde86fc3a7cdad39d8d322dbcc0da1e34d044c4f320700605a9952e67788c825b53516e5ff452e37cde127aaf902416168dc6384fe62954d336efe7aea23eb