Gavril T-series addon v0.6.0

• added the hay bale material
• fixed the silo material
• updated the 2 axle dolly to have a 'real' fifth wheel
• added a single axle dolly with fifth wheel
• Made the dollies a separate vehicle
• updated the lead trailer frame
• updated the heavy duty tow hitch
• added a reinforcement option for the flatbed to be able to carry more weight
• copied the container skins to the skeleton containers to have more container colors available
• fixed the car lift
• updated some semi presets to fix the semi pulling to one side (steering tune)