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.
`new_nonce` has been an alias for `random_nonce` for a while now. Having
two names for the same operation is confusing. `random_nonce` better
expresses the intent. The documentation for `new_nonce` talks about
guaranteeing that the nonce is different from previous ones, which is
incorrect, it's just quite likely to be different.