EnemyDrop

Enemy Drop:
     - I set it so 20% of the enemies will spawn with a power up attached (although player cant tell yet)
     - Randomly selects the enemies that carries power ups
     - Randomly picks which power up out of the three
     - GUI will tell the player whenever a power up is picked up
           - It will tell the player whenever the Multi-shot and Rapid shot power ups are picked up, even if they are already on (so the player knows that timer is reset)
           - Since it does not matter if clone is picked up when clone is already active, it will not display anything unless clone is currently inactive. 
      - Tested and it looks like it works okay.
     Note: I did not call randomEnemyDrop() in the Enemy class because enemy projectiles and spikes are also enemies. So I called it in the start method of Pawn and Swirlie. So when Crosshatch and Confetti is done, I also have to call it there too.