Translator – Done Stack As Standard Stack

There were no surprises with changing the done stack to a standard stack, which went like that of the hold stack.  The Done Stack class was replaced with a single alias to std::stack and the functions were changed accordingly.

With the change of the push calls to emplace calls, a constructor was required in the Done Item class.  The push contained arguments for the RPN item pointer, first and last token pointers, where the first and last pointers were optional (defaulting to a null pointer).  The use patterns for the push function were:

• RPN item pointer only
• RPN item pointer and last token pointer
• RPN item pointer, first and last token pointers

A similar constructor with the three arguments and the same optional arguments could have been added, but this would continue to require a null pointer for the middle use pattern.  The first and last tokens pointers could have been switched, but this could lead to confusion.  Instead, three specific constructors were added for the the above use patterns with no optional arguments.

[branch cpp11 commit ca85a259fa]