Implement non-persistent connections in a cleaner way. Every test
that offers multiple requets per HTTP connection is run twice.
First all requests are run over a single TCP connection. Then for
each requests a separate TCP connection is established. If a
requests during a persistent connection fails, a reconnect is done
as relayd cancels the whole connection. This allows stricter tests
for filters.
OK reyk@

Update and extend the regress tests to use the new grammar of the
filtering rules. Some of the filenames are based on the old grammar,
we keep them for now and just update the contents to have a
before/after comparison of the features.

Most of the work was done by Andre de Oliveira (andre@)

OK bluhm@ benno@

Improves this test to be more strict on the filter action test. Now it
dispatches 4 requests from the client and checks if the server receives only 3.
Previous functionality kept.

ok reyk

Add relayd regression tests with http filter and late connect.