DDNS tests for new test suite

Include config.h

The config.h is now implicitly included using -include option of the
compiler. After this change, config.h need not be placed at the first
position in all source files.

Conflicts:
	src/knot/server/xfr-handler.c

Conf Optimization

Auto Retransfer

refs #220

*14.102.145.in-addr.arpa. is valid dname (no wildcard!) but evident typo

refs #220

 - random test used for chain fix testing
 - manual test, some of the cases copied from the old tests, but not all.

Signing after UPDATE fixed

Fixed changeset signing after UPDATE.

Was ignoring RRSIGs related to a RRSet that was completely removed. This was a relict of old code when RRSIGs were connected to their RRSets.

Also simplified the function (and function `sign_rr_should_be_signed()`) and did some minor refactoring and polishing. Please try to check if function `sign_changeset_wrap()` is equivalent to its previous state.

Revert NSEC chain fixes due to excessive complexity of the code.

- A lot of bugs were uncovered with new tests and fixes got out of hand - the code was no longer readable (not that it was readable before)
- Totally unfeasible to fix before new zone API is done. I've fixed the code, but the result was too complex, unmaintable.

Zscanner Interface

Was ignoring RRSIGs related to a RRSet that was completely removed.
This was a relict of old code when RRSIGs were connected to their
RRSets.

Also simplified the function
(and function sign_rr_should_be_signed()) and did some minor
refactoring and polishing.

Zscanner Building

DNSSEC fixes

Two fixes in this MR:

1. Continuation of fix merged in !176. Knot was still generating RRSIGs for the old (wrong) NSEC3s, as it did not know that they would be removed. Fixed by marking nodes from which NSEC3s are to be removed, so that these are not signed in the next step. (Commit 38aeecc3)
2. Function for saving removed NSEC/NSEC3 records into changeset (`knot_nsec_changeset_remove()`) was ignoring NSEC3 RRSIGs. (Commit 8b5f08ac). This probably manifested after UPDATE - a test should be added for this case.