JFYI, a start on DDDS support

I started working on DDDS support a while back and the code is to the point where I can swallow my pride enough to let other people see it. It is far from completely debugged/tested, and it is just the analogue to "rlm_realm" for DDDS -- it does nothing but create some attributes and will be moot without corresponding lb/pool handling code in the core, and that second part is an endeavor in and of itself, especially given connection affinity challenges surrounding tunneled EAP conversations. This is just an FYI in case anyone would like to read through it, offer suggestions, or just keep track. Best place to start is probably the manpage: https://github.com/skids/freeradius-server/blob/ddds/man/man5/rlm_ddds.5