removed the ExtendedSaturationStateWriter
created n-ary combined concusion visitor to improve readability of the
code
always use the queue to track non-saturated contexts within
SaturationState; removed such queue from
ClassExpressionSaturationFactory. Some simplifications for
RuleApplicationFactory (in progress).
Contexts can be set saturated / non-saturated only within saturation
state; this is now synchronized with the non-saturated context queue,
which will now contains these and only these contexts, each exactly once