* Change rate check logic to avoid DoS attacks
* Convert rate check to use object timestamp instead of arrival time
* Update cached variables before checking for superblocks
* Ensure that last times are monotonically non-decreasing
* Bump governance manager serialization format
* Improved rate check error reporting
- make script verification a part of IsInstantSendTxValid()
- relax nLockTime for IS txes since we don't have compatibility with 12.0 IS txes anyway now (fee is lower in 12.1)
* Vote relaying changes
- Remove vote relaying from ProcessVote
- Remove vote relaying from orphan vote processing
- Relay vote in ProcessMessages (only)
* Do not relay governance objects during orphan processing
* Restore relaying of local votes
* Changed overloaded function name: ProcessVote->ProcessVoteAndRelay
* Added logging to PushInventory
* Fix LogPrint format
* Log errors found during governance syncing
* Turn off rate checks during syncing
* Turn off rate check during maintenance
- avoid processing same vote multiple times
- do not relay votes until synced
- do not ban for wrong signature of old votes
- do not check masternode ranks for old votes on regular (non-MN) nodes
* refactor IsBlockValueValid to return actual error string, use it in error message for bad-cb-amount
* make error messages in IsBlockValueValid even more verbose
* Since we send all mnb's now regardless of mn state, ping check for sigTime being too old is obsolete (and wrong).
Also removing fRequireEnabled, this logic is deprecated too it seems.
* remove (pre-)enabled check in CMasternodeMan::Add
* locks in PS
* lock in governance
* locks in IS
* lock in ProcessGetData
* locks in CMasternodeSync
* centralize mnodeman.Check call
* locks order in mnpayments
* use current block chainTip when possible (less locks)
* add missing lock in CountInputsWithAmount
* fix deadlock RequestLowDataPaymentBlocks/IsTransactionValid
* LOCK2 in CheckMnbAndUpdateMasternodeList, CheckAndUpdate, SendVerifyRequest
* LOCK(cs) is not needed here
* Decouple governance init actions from serialization
Should fix this:
```
Assertion failed: lock governance.cs not held in governance-classes.cpp:117; locks held:
cs_Shutdown init.cpp:200 (TRY)
cs ./governance.h:195
cs governance.cpp:835
Abort trap: 6
```
* Increase quorum for object deletion to 2/3 of MN network
* Implement expiration of watchdog objects
* Remove objects from the watchdog map itself
* Message fix for invalid objects
- TXLOCKREQUEST should be processed as normal tx plus some custom logic, should not "fake" inventory
- should not create "fake" local lock, should instead keep track of orphan votes and reprocess them when corresponding TXLOCKREQUEST arrives
- orphan vote time map should be indexed by full outpoint, not by txid of mn collateral
bump MIN_INSTANTSEND_PROTO_VERSION
* slightly refactor IS:
- the only place where logic is changed: `ProcessTxLockVote()` - it should first try to find mn and fail if none was found and only then try to call `GetMasternodeRank()` (which is heavy)
- fixed few `cs_main`
- slightly optimized number of `tx.GetHash()` calls
- lots of `const` (fixed few related functions in main.cpp)
- few smaller fixes: iterators, log output, comments, etc
- use thread safe methods of mnodeman
- safety check in GetAverageUnknownVoteTime
