d2_client.h and .cc was split into four files:

D2ClientConfig class is now in d2_client_cfg.h/cc
D2ClientMgr class is now in d2_client_mgr.h/cc

Integrates use of NameChangeUDPSender in D2ClientMgr.

Conflicts:
	ChangeLog

Conflicts:
	ChangeLog
	src/bin/dhcp4/dhcp4_srv.cc
	src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
	src/bin/dhcp4/tests/dhcp4_test_utils.h
	src/lib/dhcpsrv/cfgmgr.cc
	src/lib/dhcpsrv/cfgmgr.h

Master updated while merging in 3299.

Also ran dhcp_ddns_messages.mes through reorder tool.

This prevents errors reported by valgrind about uninitialized value of
hops being used in unit tests which skip parsing the packet. Okayed
on jabber.

b10-dhcp-ddns uses lease length as TTL in DNS update RRsets.

Shored up the error handling in the sender when the WatchSocket fails to mark
or clear. Addes unit tests accordingly.

 - getRelayInfo() implemented, relay_ is now protected
 - setRelay => setRelayInfo
 - Option::Universe is passed as const reference
 - Further clarified white_list_ field in Subnet.h

Conflicts:
	src/bin/dhcp4/tests/fqdn_unittest.cc

Fixed a couple doxgyen errors and removed the commented
out include of ioctl.h in d2_upd_unittest.cc

Made behavior of dhcp_ddns::WatchSocket a bit more robust in handling
programmatic abuse.
Cleaned up addresses used in ncr_upd_unittest.cc, added specific test
for client side address if 0.0.0.0/port 0.
Updated copyrights as appropriate and other cosmetics.

 - RelayInfoParser now takes Option::Universe as last parameter;
 - Extra tests for checking invalid parameters in RelayInfoParser
 - Comments in subnet.h improved
 - Sanity checks in RelayInfoParser implemented, doc improved

Also added a pointer to valid message types on IANA website, in the log
message description.

 - Copyright years updated
 - Minor corrections in BINDX Guide
 - dhcp4.spec relay structure description updated.
 - new unit-test for DHCPv4 client classification added
 - new unit-test for DHCPv6 client classification added
 - fixed Doxygen errors
 - comments for CfgMgr::getSubnet{4,6} updated

Changed build request methods in d2::NameAddTransaction to set the RRset TTL
value to the value of NameChangeRequest::lease_length.

Compilation under Fedora turned a couple of missing includes,
errno.h and stdint.h.

Added creation and management of NameChangeSender to dhcpsrv::D2ClientMgr.
Added new file of unit tests, d2_udp_unittest.cc, to exercise D2ClientMgr
with a UDP sender.