This is the "server-side" part of the new friend finding system,
allowing DHT nodes to store small amounts of data and permit searching
for it. A forwarding (proxying) mechanism allows this to be used by TCP
clients, and deals with non-transitivity in the network.
These don't test anything that isn't covered by higher level tox tests.
These are also not unit tests and have never found any bug that wasn't
also caught by other tests. This makes them a pure maintenance burden.
Instead of synchronously handling events as they happen in
`tox_iterate`, this first collects all events in a structure and then
lets the client process them. This allows clients to process events in
parallel, since the data structure returned is mostly immutable.
This also makes toxcore compatible with languages that don't (easily)
support callbacks from C into the non-C language.
If we remove the callbacks, this allows us to add fields to the events
without breaking the API.
Apidsl is not powerful enough to express all the things we need and
doesn't know how `#include` works. The generated headers are more complex
than they should be.
These display some idea, but the tests are not implemented correctly. We
will need to implement the idea correctly later, but for now we can't use
these.
