UIPEthernet_1.07_ext - extended API

extended version of UIPEthernet_1.07:
(contains functionality that is not part of official Ethernet-api)

UIPClientExt: nonblocking connect, read of local- and remote port
UIPServerExt: returns instances of UIPClientExt
example code: https://github.com/ntruchsess/arduino_uip/blob/ext/examples/NonBlockingTcpClient/NonBlockingTcpClient.ino