Merge branch 'edns_opt_stats' into 'master'

src/knot/modules/cookies/cookies.c

src/knot/modules/stats/stats.c

src/knot/nameserver/process_query.c

src/libknot/packet/pkt.c

src/libknot/packet/pkt.h

src/libknot/rrtype/opt.c

src/libknot/rrtype/opt.h

src/libknot/rrtype/tsig.c

src/libknot/rrtype/tsig.h

src/utils/kdig/kdig_exec.c

tests/libknot/test_edns.c