Update ipscan to 3.7.4
Changelog:
- Allow changing of MAC address separator (many tools use "-" instead of ":")
- Cleanup some GUI resource leaks
- Comments for hosts on LAN (tied to MAC address) will now display even if MAC fetcher is not selected, or is after the Comments fetcher
- Preference added to opt-out of checking for new versions
- Calculate IPv6 range scanning percent correctly