It doesn't work at all, because we're missing something in the net code
to do with endian conversions. I haven't investigated, yet, but at least
now we have a failing test that can be investigated.
Also moved to cmake 3.5 at minimum. CMake will stop supporting lower
versions than that, soon.
Also moved to C11 from C99 to get `static_assert`.
Also made a network ERROR into a WARNING. It triggers on FreeBSD.
This library contains all the code for the old libtoxcore, libtoxav,
libtoxdns, and libtoxencryptsave. The build for toxav is still optional,
and disabling it causes libtoxcore to simply not contain those symbols
and the pkg-config file to not include opus and vpx as dependencies.
