The mechanical world stops updating after 524,288 seconds when using `f32` precision

I have created a simulator based on nphysics and I've noticed that after 6 days the mechanical world stops ticking correctly. This seems to be a floating point precision issue regarding the parameters `t` and `dt`. Using the default `dt = 1.0/60.0` then the simulator stops at exactly 524,288 seconds.

```rust
let t = 524288.0f32;
assert_eq!(t + 1.0/60.0, t);
```

While it would be possible to change the simulator to run on `f64` values, nothing apart from the time requires that precision.