this is a perquisite to support more flexible testing modes, which
could not intelligently be implemented with the old interface

... actually, it was not broken, but just very slow. I have now
reduced the number of test messages so that make check will not be
held for an extended period of time.

... this was long overdue, and I finlly tackeld it. It turned out to
be more complex than I initially thought. The next step now probably is
to actually implement multiple rule sets and the beauty that comes
with them.

also adds speed, because you do no longer need to run the whole file
system in sync mode. New testbench and new config directives:
- $MainMsgQueueSyncQueueFiles
- $ActionQueueSyncQueueFiles