changed rpn list test output to rpn list member function

the Tester::printOutput() function that output to a specified stream
was replaced with RpnList::text() and RpnItem::text() that return
strings, and updated caller

this change is needed to put the translator output as a string into the
program view
added call to clear function in destructor

user of rpn list instance no longer needs to call clear function before
deleting the instance

this required the foreach macro to be removed from the rpn list text
function, which was calling the destructor (don't understand why), and
replaced with a simple loop through each item of the list