Added basic socks5 proxy support to TCP client.
Remove useless code.
UDP can now be disabled.

new_messenger() now takes an options struct as an argument.
tox_isconnected() now works on TCP only.
Save some path nodes to speed up joining network on pure TCP.
When getting disconnected from good relay, try to reconnect.
Function to save path nodes.

Forgot to commit it with before last commit.