refs #36

refs #36

refs #36

AF_UNIX is now preferred over AF_INET sockets, although it is still
off by default.
When TCP/IP is used, default port changed from 5553->5533 (free).
AF_UNIX socket based control doesn't use (naturally) 'allow' section.

refs #36

refs #36

It is still possible to control knotd using signals though,
but the 'knotc' will use just the one configured channel not a mix
of signals and channel.

refs #36

Removed 'pidfile' config option in favour of 'rundir' for later
storage of UNIX sockets and other stuff.
Default of 'rundir' is $(localstatedir)/run/knot
Default of 'storage' is $(sharedstatedir)/knot

refs #36

- Removed functions from zone-contents - no need for them to be public.

- Mimics BIND

Two reasons:
- There's some rare race condition in the queue implementation
- Doesn't scale and current performance is almost the same (-~2%)
- Created branch with the queue still retained for future inspection

This should be properly solved by better zone fetching API with
a) refcounting b) locking.

refs #31
fixes #30

- Added a simple list to check already inserted CNAMEs
- Removed obsolote checking functions
- Nightly test will fail, because CNAME loops will be loaded and xfr-in'd

Change-Id: Ic80408a129bf42e97b9e88392d318e89cfbad3e5

(changes in scanner intentionally skipped)