News version of the Race Car Project code

What’s new :

* We changed the IRpin for the IR sensor from 11 to 3 (line 26)
* We changed the speed of the Motor 1 and 2 when the int cm is less
than 20 :
    - Motor1.setSpeed(250); -> Motor1.setSpeed(150)
    - Motor2.setSpeed(250); -> Motor2.setSpeed(150)
a few changes