Added: $startFrom, need to add few small things to it.
Added: soft-deleted streams recreation.
Changed: StickyLRUCache doesn't do excessive retries.
Fixed: added untacked file.
Fixed: deadlock in StickyLRUCache. Renamed $startFrom to $tb(truncateBefore).
Added: soft delete tests, fixed remaining bugs.
Changed: separated last event number and metadata caches in IndexReader.
Merge branch 'startFrom' into dev