Make field private
Make sure we checkpoint
Explain, add FIXMEs
Remove persistent from *RandomGrabArray*
Logging
Don't call onEncode twice
If the file is already the correct length, use it.
Make sure that it really *is* final. Need to be sure for completion.
Explain.
Add completion via truncation support to SplitFileFetcher, with a callback for ClientGetter. Not used yet.
Implement completion via truncation (ClientGetter side).
Make USKProxyCompletionCallback serializable
Fix length detection -> fix Unknown size
Logging (keep this for now)
Delete file on error.
Check disk space when creating file for completion-via-truncation.