Make tor-fw-helper summarize success status
When tor-fw-helper runs, it outputs various status information to stdout, but it is hard to tell, given this, whether it actually succeeded in punching a hole in the firewall.
I think the right place to put this logic would be in tor-fw-helper, in such a way that Tor can parse this and output a suitable log message.
Port forwarding should be considered to have succeeded if either UPnP or NAT-PMP succeeded.