This is because the tests which come later check if it has been set
to 0.

new code from merge of Trac 3008.

sending and receiving update requests with DHCP-DDNS.

around IO completion handler invocations and minor clean up.

comments. Again, these are mostly clean-up, nothing
substantial.

temporary conditional compile directives.

Conflicts:
	ChangeLog
	src/bin/dhcp4/dhcp4_messages.mes
	src/bin/dhcp4/dhcp4_srv.cc
	src/bin/dhcp4/dhcp4_srv.h

 - missing header added
 - invalid reference to prefixes removed

Conflicts:
	src/bin/dhcp6/dhcp6_messages.mes
	src/bin/dhcp6/dhcp6_srv.cc
	src/bin/dhcp6/dhcp6_srv.h

 - pointers to DHCPv4 and DHCPv6 hooks removed
 - Many methods in HooksManager are now called directly in
   dhcp4_srv.cc, dhcp4_srv_unittest.cc and alloc_engine_unittest.cc
 - Comments wrapped up differently in dhcp4_srv_unittest.cc
 - Comments clarified in alloc_engine.{cc|h}

The main change is that the list of libraries failing validation is
returned as a vector of strings instead of as a single comma-separated
string.

complained about.

receiving NameChangeRequests for use with DHCP-DDNS. This includes
abstract listener and sender classes, as well as a derivations
supporting traffic over UDP sockets.

New files added to src/bin/d2

ncr_io.h - base classes
ncr_io.cc

ncr_udp.h - UDP derivations
ncr_udp.cc
tests/ncr_udp_unittests.cc