Little update

-------- Little update! ---------

After installing a new hard drive, I've decompiled the demo and used it to reconstruct the Unity project.

While doing so, I've added some small stuff and fixed some little bugs.

• Major background update: it's now way more flexible and it's widescreen proof
• AI cars will brake when they come from behind you and are about to hit you
• Added a chronometer
• Added a "finish" message when you finish and the car will stop
• Keyboard users: you can now use ctrl and alt to accelerate and brake
• You only have to drive one lap instead of two