* clarify "cancelled periodic snapshot" message
* more rigorous checks for snapshot validity
* verify ancient blocks on import
* limit number of fed blocks
* make it possible to feed snapshot service canonical hashes
* fix failing test build
* swap ethash DAG only when more recent
* allow taking snapshot from just-restored database without error
* make creation informant less spammy
* Ancestry iterator failure-resilient
* make uncle hash searching resilient to incomplete chain
* deduce pre-chunk info from last written block's details
* to_rlp takes self by-reference
* clean up some derefs
* out-of-order insertion for blockchain
* implement block rebuilder without verification
* group block chunk header into struct
* block rebuilder does verification
* integrate snapshot service with client service; flesh out implementation more
* initial implementation of snapshot service
* remove snapshottaker trait
* snapshot writer trait with packed and loose implementations
* write chunks using "snapshotwriter" in service
* have snapshot taking use snapshotwriter
* implement snapshot readers
* back up client dbs when replacing
* use snapshot reader in snapshot service
* describe offset format
* use new get_db_path in parity, allow some errors in service
* blockchain formatting
* implement parity snapshot
* implement snapshot restore
* force blocks to be submitted in order
* fix bug loading block hashes in packed reader
* fix seal field loading
* fix uncle hash computation
* fix a few bugs
* store genesis state in db. reverse block chunk order in packed writer
* allow out-of-order import for blocks
* bring restoration types together
* only snapshot the last 30000 blocks
* restore into overlaydb instead of journaldb
* commit version to database
* use memorydbs and commit directly
* fix trie test compilation
* fix failing tests
* sha3_null_rlp, not H256::zero
* move overlaydb to ref_overlaydb, add new overlaydb without on-disk rc
* port archivedb to new overlaydb
* add deletion mode tests for overlaydb
* use new overlaydb, check state root at end
* share chain info between state and block snapshotting
* create blocks snapshot using blockchain directly
* allow snapshot from arbitrary block, remove panickers from snapshot creation
* begin test framework
* blockchain chunking test
* implement stateproducer::tick
* state snapshot test
* create block and state chunks concurrently, better restoration informant
* fix tests
* add deletion mode tests for overlaydb
* address comments
* more tests
* Fix up tests.
* remove a few printlns
* add a little more documentation to `commit`
* fix tests
* fix ref_overlaydb test names
* snapshot command skeleton
* revert ref_overlaydb renaming
* reimplement snapshot commands
* fix many errors
* everything but inject
* get ethcore compiling
* get snapshot tests passing again
* instrument snapshot commands again
* fix fallout from other changes, mark snapshots as experimental
* optimize injection patterns
* do two injections
* fix up tests
* take snapshots from 1000 blocks efore
* address minor comments
* fix a few io crate related errors
* clarify names about total difficulty
[ci skip]
