Final code for the scales task.

Old files are removed.

Description:
- All items: This folder contains the text file with all the generated
game items for the task.
- Classes: This folder contains an Excel spreadsheet with an overview of
the difficulty classes.
- Example game: This folder contains a small demonstration.
- PHP code: This folder contains the PHP code for the visualisation of a
game item.
Prolog code: This folder contains the Prolog code for generating game
items.