fixing stats for tracing and tweaking the benchmarking package to
reflect the changes in the tracing implementation (mostly the fact that
the tracing factory isn't now available from the trace state so the
stats should be accessed via the special stage executor, as for all
other stages).
cleanup
downgrading the logging level to trace
randomized tests of concurrent tracing (recursive tracing jobs are
submitted in batched and are related, i.e. jobs in the same batch share
contexts).
generalizing the class expression saturation factory and rule
application factories so that rule application can start from arbitrary
input, not necessarily with the context's root initialization. this
allows for using the machinery of class expression saturation factory
to, for example, saturate sub-contexts.
fixing the issues with interrupts during tracing (those came up when I
made tracing stage-based)