Type-specific methods and implementation class constructors and destructors

To perform type-specific operations at construction time, add a separate ImplementConstructor method to the implementation class. Call it from the class template's constructor, after the implementation class is constructed.

To perform type-specific operations at destruction time, add an ImplementDestructor method to the implementation called from the class template's destructor.

Here is the wrong way to implement the TOwningStackOf copy constructor:

  template <class AType>
  TOwningStackOf::TOwningStackOf(const TOwningStackOf<AType>& other)
      : TOwningStackOfImplementation(other)
  {
  }
  
  TOwningStackOfImplementation::TOwningStackOfImplementation(
      const TOwningStackOfImplementation& other)
      : fCount(other.fCount)
  {
      for ( unsigned int i = 0; i < fCount; i++ )
      {

fStack[i] = TypeSpecificCopy(other.fStack[i]); } }

  TOwningStackOf::TOwningStackOf(const TOwningStackOf<AType>& other)
  {
      ImplementConstructor(other);
  }
  
  void TOwningStackOfImplementation::ImplementConstructor(
      const TOwningStackOfImplementation& other)
  {
      fCount = other.fCount;
      for ( unsigned int i = 0; i < fCount; i++ )
      {
          fStack[i] = TypeSpecificCopy(other.fStack[i]);
      }
  }