TCP server testing in progress.
fix RTPHeader filling by zeros underflow

regression from 6a78e2e71c1471b89646a71a1adeb0529cfb73d4
Merge pull request #818 from maksqwe/rtp_header_fix

fix RTPHeader filling by zeros underflow
TCP server almost ready.
TCP server now has onion functionality.

All the IP/Port related structs now have __attribute__ ((__packed__))
TCP server now sends/handles ping packets.
tox_group_get_names now returns a list of name lengths along with the list of names.

TCP test now also tests pings.
Fixed bug where TOX_FAERR_SETNEWNOSPAM would be returned instead of
TOX_FAERR_ALREADYSENT when re adding a confirmed friend.
Some code cleanups.