vlib/net: add buffered IO, x.net -> net (#6754)

examples/tcp_echo_server.v

@@ -1,45 +0,0 @@
-import net
-
-// This file shows how a basic TCP echo server can be implemented using
-// the `net` module. You can connect to the server by using netcat
-// or telnet, in separate shells, for example:
-// `nc 127.0.0.1 12345`
-// `telnet 127.0.0.1 12345`
-fn handle_connection(con net.Socket) {
-	peer_ip := con.peer_ip() or {
-		'0.0.0.0'
-	}
-	eprintln('${peer_ip:16} | new client connected')
-	defer {
-		eprintln('${peer_ip:16} | closing connection...')
-		con.close() or { }
-	}
-	con.send_string("Welcome to V's TCP Echo server.\n") or {
-		return
-	}
-	for {
-		line := con.read_line()
-		if line.len == 0 {
-			return
-		}
-		eprintln('${peer_ip:16} | received line: ' + line.trim_space())
-		con.send_string(line) or {
-			return
-		}
-	}
-}
-
-fn main() {
-	server_port := 12345
-	eprintln('Starting an echo server, listening on port: $server_port')
-	server := net.listen(server_port) or {
-		panic(err)
-	}
-	for {
-		con := server.accept() or {
-			server.close() or { }
-			panic(err)
-		}
-		go handle_connection(con)
-	}
-}