increase speed implemented
decrease speed power down
increase/decrease speed powerups without changing ball.body.velocity - no bugs
Refactor power up and power down functions
Change BALL_VELOCITY_CHANGE to 1.2
Change item images
Reduce item drop chance
Reduce BALL_VELOCITY_CHANGE to 1.1
Change drop chance
Change drop chance
Merge pull request #62 from nsue/power-down-decrease-speed

Power down decrease speed