Revised Ethernet Library Client code

Thanks for the revised Client.cpp.

I had to add the two overloaded methods below to get my sketch to compile in Arduino-0017

void Client::write(const char *str) {
if (_sock != 255)
send(_sock, (const uint8_t *)str, strlen(str));
}

void Client::write(const uint8_t *buf, size_t size) {
if (_sock != 255)
send(_sock, buf, size);
}

They needed to be added because server.cpp called the following:

client.write(buffer, size)

I am not a very experienced programmer so this all may be proven wrong. Is this a good solution?