Improved Exhaust Effects

Improves the exhaust smoke effects of motorized vehicles:
- Darkens the smoke with vehicles without AdBlue (except for electric and methane powered vehicles)
- The amount of smoke varies depending on the engine temperature
- Motor load also influences exhaust smoke intensity
- Enhanced effect when starting the engine

Note: All effects (except the darker smoke) applies to all vehicles with exhaust effects, no matter if they are using AdBlue or not