dnsproxy uses sendmsg instead of sendto
dnsproxy.cc and nameserver.cc use addCMsgSrcAddr() to add a source address control message before sendmsg
This patch allows user to specify that socket binding can fail. On IPv4 there
is a ip_nonlocal_bind sysctl that can be set, however for IPv6 there is not
this call and it is unlikely to be implemented kernel-side.

Fixes PowerDNS/pdns#344
fixes PowerDNS/pdns/657

I noticed this as a result of the changes in 3.2 whereby each receiver gets its own distributor - whenever the dynhandler calls ->getBackend() it will only find the one in its' current thread, so reload won't propergate to backends within other threads.

However, I suspect this condition has always been around as a race - if I have multiple distributors and I call reload; one thread is issuing reloads while all the other backend threads are currently executing (potentially). I guess if you call reload in previous versions on a highly loaded server with multiple backends you could probably get it to crash.

The attached patch changes it so that each backend has a variable which is changed to signal that a reload or rediscover has been requested. When processing gets to an appropriate point ie before it next queries the backend database, such an operation will be run. Note that it is not run in ::get as we don't want a backend to be reloaded between performing a lookup and getting the records.

This patch means that reload/reinitialize are not done straight away as in previous versions, but on a moderately loaded server this should not be a problem as they will be performed the next time a backend is called.
rebase to HEAD
prevent duplicate slave notications caused by different ipv6 address formatting
aviod address truncation in doNotifications
Support for new automake paraller test harness
Fix execution path
Handle signals better
Use test-driver when asked
fix dual-stack superslave when multiple namservers share a ip
Revert "Check that the domain isn't already served by the new master"

This reverts commit 3b797caab6583a6a7452a0eaf45fd7a670b4242c.
don't addSuckRequest after supermaster zone creation to avoid simultaneous AXFR for the new zone
add toMasks and clear to NetmaskGroup class and use it
add only-notify option
fixes #454
closes #778
partial fix #949
add also-notify option
fixes #949
catch ComboClass exceptions in communicator
Merge branch 'master' into fix-reload
Merge branch 'master' into nonexist-fail-bind