Improve TCP server and ProxyListener

[diegows]

TCP server should provide a ready to use socket using a callback. The current implementation with a Template makes it not very flexible.

[diegows]

One example where the current implementation fails, is in the current TCP Pool server code. The Pool Client is implemented a net client type. But the current tcp pool server is a hack in the proxy listener code. Both things should be part on the network code, outside the ProxyListener.