This is currently just a nice try, since the capture part of the sniff/inspect
setup (Sniffer class) is only capturing IPv4 packets.

Don't use the IPv6 address of the host side of the bridge as if it were the system under test's IPv6 address.

In practice, this basically means not trying to detect IPv6 originating from the
system under test anymore.

Better safe than sorry, some proxy types may want to resolve every possible
hostname, localhost included, themselves rather than by querying
/etc/hosts first.

The "close the Unsafe Browser" without a "I" was a very ad-hoc optimization,
that will break on next change. Stay tuned.

This avoids using a command to run it in the test suite that is different from
the command used to run it from the Applications menu, as was the case
previously. This also avoids hardcoding information that may change.

And, by necessity, catch more kinds of sudo error messages.

... especially when the problem is supposed to be fixed already:
we do want to make sure it is, and that no regression occurs.

This includes some guidelines for writing tests.