RoR 0.15 update

The version 0.15 is out with the following improvements:

• Performance: some textures have been resized to decrease VRAM requirements, and a more efficient collision detection engine.
  
• Roads! It is easiest to drive on roads with some vehicles (like the bus), but it is not the shortest path, and it may be dangerous to cross at high speed offroad.
• A new truck. A Paris Dakar legend : the DAF Turbotwin. The original had two 500hp engines and was fast enough to compete with cars!