Adding and removal of observes is now handled by libcoap. The application's
GET handler only needs to add the Observe option (see server.c:hnd_get_time()).
This new behavior is described in Section 4.6 of draft-ietf-core-observe-12.
The idea is to send a response with code 7.31 and the token to identify
the subscription.
This change provides basic support for block-wise transfer of resource
descriptions. print_wellknown() now takes an additional parameter that
specifies the offset in the resource description where output shall start.
coap_print_link() has been modified to truncate resource descriptions that
do not fit in the given buffer (instead of failing with an error code as
was the case before).
Olaf Bergmann