examples/watrli_rpl_udp: initial commit [DO NOT MERGE, just 4 testing]

[BytesGalore]

This is a small example initializing RPL on a node and starting an UDP server.
After 30sec a message is sent to the DODAG root (DAG-ID)

[Lotterleben]

If I'm not mistaken, this creates a new socket every time is is used to send a packet... Is this intentional? If so, why?

[BytesGalore]

yup every-time a new socket.
There's no real reason for that. My initial intention was to use this function only once for testing purposes.
So the function prototype could be changed to e.g.
static void watr_li_udp_send(int sock, char* payload, size_t payload_size)
and the socket_base_close(sock); at the end of this function should be removed then.
The socket then can be created for instance here and provided as parameter here (with the new prototype).

[Lotterleben]

The main has changed a bit in the plant_node master anyway.. ;) I'd create the socket in watr_li_setup_node() and close it at the end of my new main. Thanks for the quick response!