* keep track of delta interval versions and skip deltas
that are not consequtive, i.e. when some delta message was lost
* send the delta versions in the full state gossip to sync up the
expected versions after dropped deltas
* implementation of deltas for ORSet
* refactoring of the delta types to allow for different type for the
delta and the full state
* extensive tests
* mima filter
* performance optimizations
* simple pruning of deltas
* Java API
* update documentation
* KeyId type alias
* Use InternalApi annotation
* fix merge issues of DataEnvelope and its pruning
* simplify by removing the tombstones, which didn't work in all cases anyway
* keep the PruningPerformed markers in the DataEnvelope until configured
TTL has elapsed (wall clock)
* simplify PruningState structure
* also store the pruning markers in durable data
* collect removed nodes from the data, listing on MemberRemoved is not enough
* possibility to disable pruning altogether
* documented caveat for durable data
* one Replicator per configured role
* log LMDB directory at startup
* clarify the imporantce of the LMDB directory
* use more than one key to support many entities
