Changed internal code in UdpHeader
Changed internal code in UdpHeader

All the code in UdpHeader now uses the public constants instead of
hardcoded values

jbruening/udpkit,karlgluck/udpkit,mguillemot/udpkit,karlgluck/udpkit,mguillemot/udpkit,jbruening/udpkit,jbruening/udpkit,mguillemot/udpkit,karlgluck/udpkit,jbruening/udpkit,karlgluck/udpkit,mguillemot/udpkit