Fix bugs and improve accuracy in Segmented Dedupe.
Fix segment hashlist size computation.
Remove unnecessary sync of segment hashlist file writes.
Pass correct number of threads to index creation routine.
Add more error checks.
Handle correct positioning of segment hashlist file offset on write error.
Add missing semaphore signaling at dedupe abort points with global dedupe.
Use closer min-values sampling for improved segmented dedupe accuracy.
Update proper checksum info in README.