* Temp storage for the private state added
* Temp storage for the private state added
* Request message added
* Store and retrieve offchain state logic
* State sync cache
* Private state column added to key value db
* Private state column added to key value db
* Indexing stored states via its hash
* Works with errors changed
* Private state stored into the local db
* Access to private state db added to sync io
* Private state db file added
* Rlp packets for retrieiving private state data added
* Handling of private sync completed message
* Test code fixed
* External flag for offchain storing added
* Test for private state sync added
* Saving private state logic corrected
* Migration code corrected
* Fixes after merge with master
* Merge with head
* Additional checks for slices
* Log for private state retrieval added
* Limit time of retrieving private states
* Store required hashes for every request, mark them stale if needed
* Store requested private state hashes and check received data
* Log stale requests
* State insertion fix
* Refactoring of how logging passed to state store
* Heapsize removed, syncing hashes structure reworked
* Check state length returned by contract
* Get rid of OverlayDB
* hash-db version updated
* Test fixed
* One more test fixed
* Journal for private txs added
* Tests after adding logging to private tx fixed
* Logs getter and tests added
* Time and amount limit for logs added
* RPC method for log retrieving added
* Correct path name and time validation implemented
* References for parameters added, redundant cloning reworked
* References for parameters added, redundant cloning reworked
* Work with json moved to the separate struct
* Serialization test added
* Fixed build after the merge with head
* Documentation for methods fixed, redundant field removed
* Fixed error usages
* Timestamp trait implemented for std struct
* Commented code removed
* Remove timestamp source, rework serialization test
* u64 replaced with SystemTime
* Path made mandatory for logging
* Source of monotonic time added
* into_system_time method renamed
* Initialize time source by max from current system time and max creation time from already saved logs
* Redundant conversions removed, code a little bit reworked according to review comments
* One more redundant conversion removed, rpc call simplified
