Fix parameter name in header file for show_ip_conf().
whowas: Use the normal rules for IP visibility.

Add the flags (auth{} spoof, dynamic spoof) to struct Whowas and add a
show_ip_whowas().

Normal users now see IPs of unspoofed users, and remote opers can see IPs
behind dynamic spoofs. Also, general::hide_spoof_ips is now applied when
the IP is shown, not when the client exits.