Sets the specified formatter object to be the formatter for all handles in this cache.
int SetFormatter( CHandleFormatter<T>* formatter );
A pointer to an object derived from CHandleFormatter<T>*.
Once the object has been passed to SetFormatter(), the object
is owned by the HandleCache, and will be deleted by it
at the appropriate time.
The developer should not delete instances of formatters
that have been passed to SetFormatter().
The developer should not create instances of formatters
on the stack; they must be created on the heap,