removing an obsolete class
refactoring to make the concept of "local saturation state" reusable.
currently it is used to iterate over conclusions which belong to a
certain context. also splitting the main saturation state interface on 2
s.t. the basic one doesn't provide methods which deal with
marking/unmarking contexts as unsaturated.
clean-up
a more or less stable non-recursive context tracing implementation based
on a reusable local saturation state (used to iterate over conclusions
of an existing context)
adapting the post-processing stage which checks that tracing information
has been computed for all conclusions. now it does so only for traced
contexts and is OK with discontinuity as long as the chain of inferences
only breaks at conclusions which belong to not yet traced contexts.