Some minor tweaks

Use power instead of force for acceleration.

A comment on this code:
```
float throttleOutput = clamp((2.f/3.f)*outputs[0] + (2.f/3.f), 0.f, 1.f);
float brakeOutput = clamp((2.f/3.f)*outputs[0] + (1.f/3.f), 0.f, 1.f);
```
This causes throttle and brake levels to always be in sync. Is it on purpose?