more bugfixes (esp. w.r.t. hashing)
collections tweaks
collections updates (again)
removed meta-level continuations for atomic evaluation (esp.
evalIdentifier)
removed write set, invocation (mark) now is (clo, args)
strict mode
performance enhancements: cached bump hashCode for Pair, fw/bw adjacency
Graph
gc as in formalization: narrowing benv to freeVars at each opportunity;
removed benv narrowing when creating EvalState, added benv narrowing
when creating InitState