Make rtdealer.clj similar to rtreq.clj

Both the text and the C examples treat rtreq and rtdealer as being identical except for the change from req to dealer sockets. This changes rtdealer to mirror the structure of rtreq.

If you diff it with rtreq.clj, you'll see that the change is quite minimal. I'm not sure why the existing rtdealer diverges so much from rtreq.