delaying the requirement of pf::enforcement

- improves performance (marginally I would assume)
- prevents pfcmd to start 'from harder to prevent' requirements
inlined Parse::Nessus::NBE

it hasn't changed in 8 years and it's never packaged..
removed Net::MAC dependency, replaced by our pf::util::clean_mac
inlined Net::MAC::Vendor

it hasn't changed in 5 years, it's never packaged and it's arch independent
debian: removed dependency from previous commit

libnet-mac-vendor-perl, libnet-mac-perl are out

slightly updated NEWS too
default dhcp values provided for networks.conf

dhcp_default_lease_time and dhcp_max_lease_time
MIME::Lite::TT now optional

Also `checkup` will issue a warning if it's required because of an
activated feature.
reversed the other of ownership tests

Changing owner removes any setuid bits so it made little sense to report
the problems in that order.
taint mode sprintf usage fixes