simplified and thus speeded up the queue engine, also fixed some
potential race conditions (in very unusual shutdown conditions)
along the way. The threading model has seriously changes, so there may
be some regressions.
NOTE: the code passed basic tests, but there is still more work
and testing to be done. This commit should be treated with care.
Well, actually this and a lot of related things. I improved the
testbench so that the new capabilities are automatically tested and
also did some general cleanup. The current multiple tcp listener
solution will probably receive some further cleanup, too, but looks
quite OK so far. I also reviewed the way tcpsrv et all work, in
preparation of using this code for imdiag. I need to document the
findings, especially as the code is rather complicated "thanks" to
the combination of plain tcp and gssapi transport modes.
