[tor-project] support the torproject with bridges

[Roger Dingledine]

On Thu, Aug 10, 2017 at 02:32:00PM -0700, David Fifield wrote:
> > The bridges nat's to real guard IPs. A mid relay will never see the bridges
> > IP. ok ?
> 
> That is okay.

That is more than ok -- it is a nice feature. :)

It takes care of attacks 2, 3, 4, and 5 on
https://blog.torproject.org/blog/research-problems-ten-ways-discover-tor-bridges

--Roger