ref #103

- DNSSEC planning function no longer cancels the previous signing event, added explicit cancel before calling the function where applicable.
- Removed locks with zd->lock

Refs #151

Refs #254

ref #254

refs #220

This reverts commit f6ca14ae.

Conflicts:
	tests-extra/functional/tools/dnstest.py

- Locking more granular in DNSSEC planning function (needed only when reading values from zonedata)
- Fixed removing of just planned DNSSEC event (GOTOs FTW ...)

Refs #253

Fixed CID#1128355, CID#1128356, CID#1128358

This test requires following binaries in PATH or set via env variable.
* 'java' (since PROTOS is written in Java...), env: PROTOS_JAVA_BIN
* 'c09-dns-query-r1.jar', env: PROTOS_QUERY_BIN
* 'c09-dns-zonetransfer-r1.jar', env: PROTOS_ZONETRANSFER_BIN

Basically this creates a Dummy master and runs the PROTOS tools
to serve zonefiles and try various queries.

See https://www.ee.oulu.fi/research/ouspg/PROTOS_Test-Suite_c09-dns

This is used in PROTOS test for example where the 'Dummy' server
still provides assigned port, allows master -> slave linking and
so forth. Non-existent zone files are needed because the zone may
be bootstrapped from the external tool.

- created knot/server/zone-load.{h,c}
- some API calls exposed from knot/server/zones.h

ref #255

refs #251