[MEDIUM] add non-local bind to connect() on Linux

[MEDIUM] add non-local bind to connect() on Linux

Using some Linux kernel patches which add the IP_TRANSPARENT
SOL_IP option , it is possible to bind to a non-local address
on without having resort to any sort of NAT, thus causing no
performance degradation.

This is by far faster and cleaner than the previous CTTPROXY
method. The code has been slightly changed in order to remain
compatible with CTTPROXY as a fallback for the new method when
it does not work.

It is not needed anymore to specify the outgoing source address
for connect, it can remain 0.0.0.0.