[master] Merge branch 'trac2765'

diff --cc doc/devel/mainpage.dox
Simple merge

diff --cc src/bin/dhcp4/dhcp4_messages.mes
Simple merge

diff --cc src/bin/dhcp4/dhcp4_srv.cc
Simple merge

diff --cc src/bin/dhcp4/dhcp4_srv.h
Simple merge

diff --cc src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
Simple merge

diff --cc src/bin/dhcp4/tests/dhcp4_test_utils.h
Simple merge