rpn list: replaced text function with put stream operator

removed the rpn list class text function and replaced it with a nearly
identical function in the tester class source file that overloads the
put stream operator ("<<") for an rpn list instance except that is
outputs directly to the output stream argument (instead of to a local
string stream variable), uses local index variable to detect the
beginning of output (instead of the position in the string stream), and
returns the output stream reference (instead of the string in the string
stream)