changed how dns deals with cnames and recursion: remember cnames and implement recurs...

changed how dns deals with cnames and recursion: remember cnames and implement recursive lookup here using DnsResolvers that are not saved in DnsMaster.

Experiments with own name server and recursive cnames showed that TTLs are not always the minimum.
This way we have better control about resulting TTLs
and debugging is easier since DNS caching is avoided.

Also create unique id for each dns message and check reply
and in main warn if using debug option max_exceptions.