+ added the basics to shooting with a direction
- TODO:
* check if the pistol should use gravity
* add the intensity parameter!
* discuss if it should draw a straight line with the direction for shooting assistance
* check if [self.parect addChild: projectile] should be changed to [self addChild: projectile] to avoid shooting myself
* discuss the steps to shoot with intensity (slide for direction, then hold for power?)
EOL