First working backspace implementation.
Backpace now working. Removed cursor keys. Will add them in a branch
Replaced the start() methond with a readline() method. Means que class
should only read a string input by the user and pass the processing of
that string to the calling code. readline() reads one line at a time.
Added addline() function so new lines can be added to the output window from outside the class.
Adding a very simple demo script