Bag/Tally _IRep* CTORs replaced with SharedPtr... CTORs; and renamed Tally_Array/Tally_LinkedLists's MutatorRep_ class as IteratorRep_
cleanups (tally/bag)
lose bool   operator== (const TallyEntry<T>& lhs, const TallyEntry<T>& rhs): instead use TallyEntry member function version
used operator==/!= members with Tally<> intstead of global functions
minor cleanups of Tally code (added a few simple overloads of Add())