Get rid of duplicated log IDs
I didn't find it in any of our coding guidelines but it has been one of our best practices since the beginnings of Kea that there are no duplicated log message IDs in the code. Each log message should come with a unique ID so it is possible to localize the source of the log message. It looks that we have duplicates in some places, (e.g., DHCP4_PACKET_PROCESS_STD_EXCEPTION
). I think we should remove the duplicates and/or document coding guidelines for avoiding the duplicates.