I've finally got few spare time to play a bit more with my SandBox-PlayGround ...
Here is an updated version which mainly add a TCPServer (using the WifiServer ESP8266 library).
It provide a Telnet access to most of the previous pseudo-shell commands accepted on UART port previously.
(I will probably throw away this uart code now that the ESP module is reachable thru telnet, freeing the port to do something else, maybe another TCP-RS232 Transparent Bridge ... )
But, still, there is an issue : it is not yet multi-clients !!! see viewtopic.php?f=32&t=2612 ...
But, I'm confident
BTW, if anyone wish try it out, at least on Linux, you need to specify port even if my server is listening on 23, so "telnet <ipaddr> 23", not "telnet <ipaddr>", otherwise the telnet client will try to negotiate something that will make connection fail (maybe another bug related to lower layer of ESP)
Ciao !