Added the kill frames

I intended to implement a way to kill the enemies via a powerup akin to Pac-Mans Power Pellets (helps to keep it one button as well).

Initially I was going to just change the sprite and code the hitboxes to do something different. Ended up being easier to just make a new object over the turtle to do that job. Also made is more visual. I also tweaked the turtles powered up mode to be more visible as well. Ninja Turtle shoutout.

The effect is very cheesable, but its fine for now.

I also made the jellyfish drift down a bit more as they still like to hover near their spawn point, which right now is off the screen.

Fixing the shark is still TBD, and so is maybe adding some ui for level changes. Also general polish.

On a bigger note, I didn't have to band my head against the wall for this project. Most of what I implemented, I already knew from past projects. I think I'm getting better at wrapping my head around the various systems.