Returns a list with each script that is triggered.

def trigger_hats(self, command, arg=None, callback=None):
        """Returns a list with each script that is triggered."""
        threads = []
        for scriptable in [self.project.stage] + self.project.sprites:
            threads += self.trigger_scriptable_hats(scriptable, command, arg,
                                                    callback)
        return threads