Refactorization

To ease my future work I refactorized my previous Button and Entry class that I used it the image browser project, and made one Interface class from them. Much more simple. Beside some refactorization I created a resource loader, it will be great help at next Pyweek. You can load images, text files and sound into a dictionary which grant easy access to resources. I wrote a small code to demonstrate their work. They are under GNU licence, so feel free to download them from here.