Changelog:
991cebb Retry send DNS response without extra section
4e14439 Handle DNS Rcodes
1bf7946 Delete filterlist entry if update has no sources
c856b73 Improve handling of expired or failed queries
34247b1 Add hearbeat check to TCP resolver
3c6cd69 Add support for default ports nameserver config
1b11d15 Add ServerInfo to resolvers and caches
3f3d82b Improve debug information in DNS responses
f46e759 Use new Purge method of the database
ba59672 Fix updates restart task not being started