general cleanup items for containers

• move some HashTable details into the Detail namespace

• avoid delete/new when calling HashSet::set()

• better handling of pointers in hashes (IO).

• FixedList output formatting influences pair/edge and thus we get things like 2{100} for a labelPair output. For these short lists it probably doesn't have much space saving. It would be nice to have the same output format for a Pair or a Tuple2 of the same content.