* Since we send all mnb's now regardless of mn state, ping check for sigTime being too old is obsolete (and wrong).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
* Move vote relaying into ProcessVote so that local votes are relayed
* Change signature of Insert method to return indication of whether insertion succeeded
* Only process orphan votes once
* Fix function name in log messages
* Fix CGovernanceManager initialization problem
* Added logging messages for cases where CGovernanceManager receives a message while not synced
* Prevent potential NULL pointer dereference
