Adding some simple running mechanics, pressing the left shiftkey doubles the character's MAX_SPEED and doubles the animation speed of his move animation.
Moving the logic to mutate collectable objects from DefaultState to a module method in collectable.py.
Making sure to use consistent spelling for "collectables"
Making a Collectable object that won't become invalidated when the sensor object is removed. Also, CollectableSensors now remove themselves from the collectables list, and DefaultState just detects when all the collectables are gone.
The speed multiplier for running is now controlled by a RUN_MULTIPLIER variable.
Adding the ability to have unique collectables, and adding a speed boosting collectable as an example.