Fixing memory leak when using nameserver discovery and NetworkAddress…

…Changed events (MichaCo#68)

Removing usage of NetworkChange.NetworkAddressChanged usage to refresh discovered name-servers.

Auto detect network name server changes (MichaCo#66)

* Using `NetworkChange` event to react on changing network adapters
* Periodically re-run `NameServer.ResolveNameServers` to check if the configuration changed

Calculated ttl rework. Updated unit tests after PR merge MichaCo#30

Reorganized testing zone files

Adjusting adit log to give more information on server errors and to n…

…ot print the message if there are no more servers

Forgot one checkin

Version suffix change

Trying to fix nameserver resolution on linux (Permission issues) Mich…

…aCo#3

more testing: for loop into array wins

Run remote dns server unit tests only in debug (not on appveyor)

Some more unit tests, enabled caching per default, enabled tcp fallba…

…ck per default. Changed all DnsName references in records to actually return DnsName type (not a big difference as it casts to string).