Worked for a full day on pda logic. Ended up starting over fresh and created the state and pushdown classes, which are analagous to the PDA and Node classes. They are laid out more logically and make more sense. Also full integration with calculator and main. Added an option in the menu to switch on or off PDA mode. In PDA mode, you enter in an input string instead of two individual numbers.
Prior commit failed. Hoping this one works
Merge branch 'master', remote branch 'origin'
Deleted defunkt PDA and Node classes.