Merge pull request #1182 from mind04/ipv6

Ipv6 master improvements and new also-notify/only-notify options. Closes #778, closes #454.

diff --cc pdns/common_startup.cc
Simple merge

diff --cc pdns/dnsproxy.cc
Simple merge

diff --cc pdns/pdns.conf-dist
Simple merge

diff --cc pdns/tcpreceiver.cc
Simple merge