fixes #211

Conflicts:
	src/knot/server/zones.c

Zonefile loading fixes

Most is said in the commit.
I would have refactored zone-load more (especially the custom rrset lists could be standard ptrnode_t list from list.h) and a few other things,
also it should be named something like `zonefile.h` as we already have a `zone-load.h` file which is for zone loading in general and makes it confusing.
But I didnt, as @jkadlec made a lot of changes in the rrset->rrsigs and I suspect this would result in nasty collisions (like the rrset lists code).
So... this should be done after his branch is merge-able.

NSEC/NSEC3: Fixed wildcard expansion proofs and previous node lookup + tests

Most of it is written in the commit comments, it's still not pretty but at least it works for now.

- refactored the zone-loader a bit, as reading from zone file
  creates only contents and the zone is created separately
- refactored zone contents creating function, as it is always used in a
  way where an apex node is created and inserted into contents
- crash occured because created zone bound configuration and if parsing
  failed, the configuration was freed with the zone and also with the
  caller

cov#1165386

cov#1165387

cov#1168292

cov#1169882

cov#1165390

- new test for wildcard expansion leading to NXDOMAIN
- new test for wildcard expansion leading to NODATA

authoritative

- this is temporary, as looking up closest encloser and previous
  is not required (or doesn't make sense) in all situations
- zone search should always return lexicographically previous node
  and the proof code should look up the encloser or previous node
  should it be needed

- every RFC5155 state may have visited a wildcard in processing,
  therefore they need to be proven
- fixed duplicate NSEC wildcard proof in no data case

- previously parent was added for MISS state, not the wildcard child
- removed deprecated MISS masking after following CNAME chain, as
  names leading out of zone are handled correctly

Added test cases for this and previous commit.

Conflicts:
	src/libknot/nameserver/name-server.c

UPDATE forwarding fixed to work with the current API

I'd like to run `tests-extra` as part of the nightly tests soon, so we can root out the old test cases.
UPDATE forwarding was disabled until now, I enabled it to work with the current API until it is reworked.

Remove Integrity Check

This is going to be reworked with the new response processing API,
but it needs to be working for the tests.

* origin/merge-nameserver-server:
  evsched: updated comments and renamed some attributes
  evsched: add missing header
  evsched: removed deprecated evqueue and streamlined the API
  remove void comments
  minor formating fixes
  utils: renamed knot_serial_compare and added headers
  zone: common API for controlling zone timers
  nameserver: Merged nameserver_t -> server_t
  nameserver: removed redundant attributes

zone: use just one free function

Fixes broken build on some distributions.

* events now carry pointer to their scheduler
* no event types, events are simple callbacks
* removed unused or deprecated stuff
* bugfix: zone never expired since expire was initialized on create
* bugfix: race condition on rescheduling events
  - there is always some time between cancel and schedule
  - if two threads run run past the cancel and then race for schedule,
    they may rarely schedule an event two times
  - this is hard to deal with unless we place a lock on the zone
    operations, therefore each schedule checks heap if the event is not
    already scheduled and if it is, it replaces the old instance

Several NSEC(3)-related bugs fixed

1. When replying NODATA response from empty non-terminals, NSECs for NXDOMAIN have to be added instead of NSECs for NODATA. (Does not apply for NSEC3.) This was not handled in the rewritten query processing.
2. When adding RRSet to node, do not increase RRSet count of that node, if the RRSet is empty and contains only RRSIGs. Such RRSet was counted and it resulted in wrong behaviour when RRSet was removed but its RRSIG remained in the zone. (Note that in current implementation the RRSet count in node reflects only RRSets directly in the node, i.e. it does not count RRSIGs).
3. In some cases, NSEC3 records were generated for empty non-terminals that were subsequently deleted after applying the DNSSEC changeset. See issue #210 for description and solution.