[MAJOR] http: fix again the forward analysers

[MAJOR] http: fix again the forward analysers

There were still several situations leading to CLOSE_WAIT sockets
remaining there forever because some complex transitions were
obviously not caught due to the impossibility to resync changes
between the request and response FSMs.

This patch now centralizes the global transaction state and feeds
it from both request and response transitions. That way, whoever
finishes first, there will be no issue for converging to the correct
state.

Some heavy use of the new debugging function has helped a lot. Maybe
those calls could be removed after some time. First tests are very
positive.