Implement local_connect_enable option

[EtiennePerot]

Building upon a patch from issue 28 on Google Code, this implements an option (local_connect_enable) in torsocks.conf which allows connections to local addresses.

The option is disabled by default (i.e. local connections are refused), and connections to port 53 are blocked unconditionally (regardless of the value of local_connect_enable).

This also includes an updated man page and test output.