Please describe the problem:
I am using Pan for large binary downloads and I have found a very annoying 
behaviour when working with multiple servers. Let me explain:

Some servers I use offer a free account but with daily download limits, and 
some others are not 100% time up. When I am downloading stuff from some server 
and it fails (or just rejects my connection due to daily limit reached) pan 
shows an error window reporting that was "Unable to connect to server XXXXX" 
and it automatically goes to disconnected mode for all servers, making the use 
of alternative servers impossible.

I would like Pan to be "wiser" in this situations and just go and use other 
servers silently. Maybe it would be a good idea to mark the failing servers 
internally in some way just to not try to connect to them in some amount of 
time but never stop the queue when there are alternative servers to download 
stuff from.

The server response when the daily quota has been reached is:

502 news.XXXXX.com: Access denied to your node

Also usually try "test servers" that usually are up and down, or sometimes 
returning "502". IMHO Pan should handle these errors in a "non-critical" way 
and don't go to offline mode so quickly.

Steps to reproduce:


Actual results:


Expected results:


Does this happen every time?


Other information:
this is as version 0.116