added basic roads, some collision detection and flashing screen during collision, controls for second frog, and second car
Properly implemented the game timer.

But unfortunately this does not solve all of our timing problems because the loop won't be called
EXACTLY the same time each time. Therefore we need to modify all movements to incorporate the
current tick time. So that when the tick time it a bit higher everything thing will move a bit
further.
Logically divided up our bermyfrog into more manageable pieces.

Put all constant (yes, that is the key word there) globals into their own file.)
ZONE (the pygame window variable) is not a constant so it won't go into the constants file.
Instead each object will grab it on initialization.