Ethershield_webserver: Timing bug breaks request handling

[dekstop]

The Ethershield_webserver example works fine, but occasionally won't respond to requests. Once I added debug logging to trace the execution this problem vanished; which makes me believe it's a timing bug where something isn't waiting as long as it should before proceeding.

To reproduce:

• start Ethershield_webserver example, ensure it serves requests
• make multiple requests (either manually or with apache ab: ab -n 10 <ip>
• expected result: all requests get handled fine
• actual result: some requests time out

To "fix":

• add a Serial.println(...) command after dat_p=es.ES_packetloop_icmp_tcp(buf,plen); in line 172
• re-run the test above
• result: all requests get handled fine