animation_speed_controller.py : Modified slider range
ebnf.txt : Updated to include 'repeat' command and 'endrepeat' statement
ebnf.txt : Refactored
* : Circles now draw with centre at drawing point position
about_window.py : Removed external .txt file for window content
* : Added sample .txt file
controls.py : Refactored save and load controls
controls.py : Fixed issue where new files where saved to old paths
* : Added more sample .txt files
editor.py : Implemented line numbers
* : Refactoring
editor.py : Refactoring to comply with pep8 standards
* : Fixed issue with line numbers overlapping
* : Refactoring of secondary windows