Fixed: DDNS retcode not propagated, rollback on wrong journal instance.

First one falsely reported UPDATE success even though it failed to serialize.
Second issue treated journal as full when transaction failed to write all
changes. This is harmless, but it broke tests.
Merge branch 'ddns_rollback_fail' of /git/repositories/knot
config: add option for maximal udp payload

refs #159
man: update knot.conf.5
Merge branch 'set_edns_payload' of /git/repositories/labs/knot
nameserver: fix UDP payload size

Maximal UDP payload size is 512 B (excluding UDP header)
RFC 1035 #4.2.1
libknot: remove correlation between EDNS0 max udp payload and TCP message size

refs #160
typo
Merge branch 'tcp_payload_fix' of /git/repositories/labs/knot
Add beNNtoh support for glibc < 2.9
Merge branch 'byteorder' of /git/repositories/labs/knot
zscanner: add check for unclosed multiline block
config: properly close included files

refs #162
Merge branch 'config-includes-fclose' of /git/repositories/labs/knot
configure: enable all compiler warnings

refs #166
zscanner: revert changes committed by mistake
DDNS: fixed double switch when appling DNSSEC changeset.

 - Fake zone created and changesets are applied to that zone.

Refs #4
DDNS/DNSSEC: small fixes before changeset applying.

Refs #4
configure: enable all compiler warnings

refs #166
Merge branch 'compiler-wall' of /git/repositories/labs/knot