Major Description
We should remove ProtocolNetAccept. ProtocolNetAccept is used to issue an initial read request so that the leading bytes of the client session can be snooped to detect the protocol being issued by the client. However, I'm pretty sure that this can be implemented directly by ProtocolAcceptCont neé ProtocolDetectSessionAccept using the same technique that is used for SSL NPN and ALPN. Additionally, we should remove the probe state from UnixNetVConnection, which we can do either by adding a peek operation to NetVConnection, or continuing to use do_io_read, but retaining the buffered data and passing that on to the client session state that we subsequently spawn.
