* Aristo+Kvt: Better RocksDB profiling
why:
Providing more detailed information, mainly for `Aristo`
* Aristo: Renamed journal `stats()` to `capacity()`
why:
`Stats()` was a misnomer
* Aristo: Provide backend read caches for key and vertex IDs
why:
Dedicated LRU caching for particular types gives a throughput advantage.
The sizes of the LRU queues used for caching are currently constant
but might be adjusted at a later time.
* Fix copyright year
b9187e0493