Update to Go 1.3 + timeout + get stream for large e-mails

I included a timeout by default because eventually the program halted on the net.Dial indefinitely;
The TLS version uses the new (Go 1.3) function `tls.DialWithDialer`;

GetRawMailStream is used when you don't want to dump the whole email in memory (like when dealing with large attachments);

The quit command closes the TCP connection even when the command fails to avoid having ghost connections open (if you often open/close connections);