Merge ITcpAdapter with CRtdsAdapter

Now that CPscadAdapter is gone, CRtdsAdapter is the only child of
ITcpAdapter. We don't forsee ever inheriting from ITcpAdapter again, so
let's merge it with CRtdsAdapter to simplify the system.

Also, deleting code is fun.
CRtdsAdapter: fix includes
CRtdsAdapter: more fixups
Merge pull request #323 from FREEDM-DGI/ByeITcpAdapter

Merge ITcpAdapter with CRtdsAdapter