Buoyancy

[noebm]

I have some half finished buoyancy code using bevy_rapier. Do you think that fits in this library when its finished?

I'm somewhat hesitant to add dependencies.

[Neopallium]

Could use a feature flag. A lot of games will most likely be using bevy_rapier already.

I think it would be a nice feature for this library. I haven't worked with rapier yet, but plan to use it in the future (different project).