[PATCH] Comm::TcpReceiver - part 1, 2, and 3

Here we have the combined patch for what I have been calling part 1 -
Comm::TcpReceiver interface, part 2 - ConnStateData object API upgrade,
and part 3 - HttpStateData object API upgrade.

I makes for a huge patch once again, but I hope this combined form helps
to clarify the interactions for a better audit.

* Kept the TcpReceiver name for now since Alex is disagreeing with
callign the interface an "agent". I am thinking of calling it just
"Comm::Tcp" in its current form.

* The clear thing to keep in mind is that this TcpReceiver object is
*just* the interface design for the I/O actions. It needs to be
inherited by some other object which performs the processing logics on
the I/O data.

* this version adds sendSomeData() method for the write operations.

Amos