made UPnP ignore devices that don't respond from a router IP (optional but on by default)

docs/manual.html

@@ -2458,6 +2458,7 @@ struct session_settings
         int inactivity_timeout;
         bool use_dht_as_fallback;
         bool free_torrent_hashes;
+        bool upnp_ignore_nonrouters;
 };
 </pre>
 <p><tt class="docutils literal"><span class="pre">user_agent</span></tt> this is the client identification to the tracker.
@@ -2565,6 +2566,10 @@ needed anymore since the torrent won't download anything more). If it's set
 to false they are not freed. If they are freed, the <a class="reference" href="#torrent-info">torrent_info</a> returned
 by get_torrent_info() will return an object that may be incomplete, that
 cannot be passed back to <a class="reference" href="#add-torrent">add_torrent()</a> for instance.</p>
+<p><tt class="docutils literal"><span class="pre">upnp_ignore_nonrouters</span></tt> indicates whether or not the UPnP implementation
+should ignore any broadcast response from a device whose address is not the
+configured router for this machine. i.e. it's a way to not talk to other
+people's routers by mistake.</p>
 </div>
 <div class="section">
 <h1><a id="pe-settings" name="pe-settings">pe_settings</a></h1>