Parameter interaction: disable upnp if -proxy set
Parameter interaction: disable upnp if -proxy set

To protect privacy, do not use UPNP when a proxy is set. The user may
still specify -listen=1 to listen locally (for a hidden service), so
don't rely on this happening through -listen.

Fixes #2927.

syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin