Progress on Difficulty

I freed up some variables in the movement section being that Bag Boy's X and Y movement are the same value. I then used those variables for the additional cars so that I may link their movement to a separate one as difficulty progresses. I will next try and determine how to best adjust values as score progresses to make it more difficult.

Once I have the mechanics figured out I will work on a power up or two,  like an energy drink that allows for faster movement when the button is pressed but I do not want to implement that until I can figure out a status bar because I will undoubtedly want some kind of timed element to keep the game moving.

I had also did some minor housekeeping and improved on the playfield graphics.