The following has been done:
* rename tox_{get,set} to tox_self_{get,set}
* rename tox_{get,set}_friend to tox_friend_{get,set}
* use *_size() functions instead of a return status
* pass NULL to discard error handler in _friend_ functions
Now we support both HTTP and SOCKS5 proxies. While at it, get rid
of the outdated usage string and just establish the fact we have
a bloody manpage for explanations.