vtkDebugLeaks registers instance by class name, which worked well for
many years. However, now that we have more templated code, this is
becoming difficult. For instance, "template <typename T> vtkBuffer<T>"
would be identified as "vtkBuffer<T>" when registering with
vtkDebugLeaks, but deregistered with the compiler dependent
typeid(vtkBuffer<T>).name() string returned from GetClassName().

This patch moves vtkDebugLeaks registrations to the method
vtkObjectBase::InitializeObjectBase(), which must be called after the
vtkObjectBase is instantiated. This ensures that objects are
registered using the same string as when they are destroyed. In
general, a call to "new vtkSomeClass" must be followed by a call to
InitializeObjectBase on the new instance. The common ::New()
implementation macros in vtkObjectFactory will ensure that
registration happens correctly.

Two notable exceptions are vtkCommand and vtkInformationKey
subclasses. These do not require any specific handling...