Terminate the getter.
Logging
Fix error on cancelling a fetch.
Fix deadlock/major concurrency issue: Never run the heavy callbacks in the memory limited job thread! Can start new stuff before the old job is finished -> boom.
Fix not reporting progress.
Fix streamGenerator (we *need* to close the stream, or it will stick forever).
Support maxRetries != -1, i.e. splitfiles with finite number of retries, e.g. important for fproxy, and give feedback on failed blocks.