Rename fr_pton functions to fr_pton4, fr_pton6 and fr_pton. fr_pton will resolve the IP address to either 4 or 6 based on format and/or available DNS records.
Add PW_TYPE_COMBO_IP_PREFIX (conffile parser only)

Change 'ipaddr' to PW_TYPE_COMBO_IP_PREFIX so we can be really lazy about IP formats
Rename PW_TYPE_IP* so they're all consistent