udp echo server and client use them they r working fine

echo的客户程序，很有用的调试工具，实现tcp和udp协议的客户端，下程序为tcp-echo client program, a very useful debugging tool, tcp and udp protocol client, under the procedures for tcp

this code shows how to use the Spi_Ethernet mini library : * the board will reply to ARP & ICMP echo requests * the board will reply to UDP requests on any port : * returns the request in upper