How to use / write Plugins:
 - http://wiki.laptop.org/index.php?title=XO_ImageQuiz/Plugins
 
 List of Services:
 - ImageQuiz.py, Line 37: "Hook-In Services"
 - http://wiki.laptop.org/index.php?title=XO_ImageQuiz/Plugins#Overview
 
 Services can accessed via the Class __SERVICES__
 __SERVICES__.db.query(q)
 __SERVICES__.db.commit(q)
 __SERVICES__.frontend.add_menu_item(path, caption, onclick_function)