COMP: resolve label-size=64 ambiguities

* The generic templated constructor and assignment
  Eg,
     template<class ListType> DynList(const ListType& lst)

  Provides the best candidate when there is a int32/int64 mismatch:
     DynList<int64_t> list(10)

  The cleanest solution would be avoid the generic templated versions
  entirely, but they are needed when converting from rows of graph data
  (which are stored as LongList). However, this approach introduced some
  odd regressions.