* 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
* Fix exit codes:
- `--help`, `--version` etc should exit with `0` i.e. no error ("not enough args" case should still trigger an error)
- error reading config file should exit with error
- slightly refactor AppInitRPC/AppInitRawTx to return standard exit codes (EXIT_FAILURE/EXIT_SUCCESS) or CONTINUE_EXECUTION (-1)
- every main()/exit() should return/use one of EXIT_ codes instead of magic numbers
