Added persistence for manifest
Simplified getting L2 overlaps
WIP
Added file deletion and sync operation
Implement key deletion
Make comparator public so it can be used by ycsb. update TODO
Added stats package
WIP
Speedup in reading SSTables
Performance improvements
- use concat iterator instead of merge iterator for sstables on same level
- fully compact a level each time to stop number of sstables growing
- larger buffers and flush memtable more often
Dropped flush queue size as anything above 1 is a bug right now.
Increased number of flushing memtables again
Fixed issue with manifest not loading if there's more than one level.