Change getters/setters to match the new API...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
Implement proxy functionality as desired...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of the outdated usage string and just establish the fact we have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.