1. Moved netdb's disk file operations to separate threads
2. Fast exploratory lookup handling at floodfills
3. Drop unsolicited database search replies
4. Pick only confirmed routers for tunnels and exploratory replies if tunnel build rate is low
5. More reliable long live streams
6. Throttle database search requests
7. Handle database search replies faster
8. Don't accept too old routers and address with malformed keys
9. Fixed different crashes on high load and shutdown