* Include lwip/inet.h in some unit tests and apps
* Since they use htons() and pals.
* test/unit/api/test_sockets.c:
* write() could be declared by external socket headers
* Call lwip_write() instead.
* Code expects fcntl() to return 6
* But O_RDWR could have another value if external
socket headers are present
* Replace 6 by O_RDWR.
* apps/tftp/tftp.c:
* recv() could be declared by external socket headers
* Rename it to tftp_recv()
- implement server/client mode (API is nicer to use)
- Increase TFTP_MAX_MODE_LEN to be able to contain "netascii" transfer mode
- Adapt tftp_example to changes