2.5.38 server

• Only copy hash potion of old chunkhash file on failure. This fixes incremental partial backup failures when downloading a script with indeterminate size is interrupted
• Fix issue with too small sparse extents causing patch failures
• Prevent ignoring permissions when restoring files via tokens (reported by Valentino Paulon)
• Add optional proof of work DoS mitigation to Internet authentication
• Limit max PBKDF2 iterations performed on server fixing a DoS issue (reported by Matheus)
• Timeout connection after 30s in initial state when authenticating Internet connections fixing a DoS issue (reported by Andrew Elmore)
• Add settings to allow a client to restore all clients and a setting to disable client rename detection
• Reset allow_restore_clients when updating virtual clients if necessary, making the server setting allowing all clients to restore apply without server restart
• Don’t take image backup interval into account when image backups are disabled
• Improve error handling when hashing patch
• Only startup one virtual client at a time, not all at the same time
• Remove hash threads beta setting
• Add setting to limit max number of simultaneous backups per client group
• Increase send MBR connect timeout fixing issue when this takes longer than 10s
• Improve logging for send MBR issues