bugfix in exit node choice: we used to find the perfect exit node but                            then use the wrong one.
bugfix in connection_ap_can_use_exit: it was using the wrong port
bugfix: the OP now handles a port of '*' correctly when the IP is not
  yet known and it's trying to guess whether a router's exit policy
  might accept it.
we now don't ever pick exit routers which will reject *:*
attach_circuit now fails a new stream outright if it will never work.
when you get an 'end' cell that resolves an IP, now it will fail the                             circuit outright if no safe exit nodes exist for that IP.
don't try building a new circuit after an 'end' if a suitable one is
  already on the way.


svn:r874