make sure update/draw exists before calling em
don't call setup when switching to orig game state from editor
don't call setup when switching to orig game state from editor
fix default arguments
respect snap_to_grid when creating new objects
add support for data-property (used by editor to add ocustom data to sprites)
refactor left/right click into separate functions + detect dbl clicks
attributes() should return shallow copies for easy cloning
make game_objects, save and exit public properties for easier debugging
move the most important part from deprecated SpriteList into Sprite, the ability to load sprites from serialized string, this is what we use to create sprites from serialized data that the editor produces