Function duckduckgeo::repel_one

pub fn repel_one<N: Float + MyNum>(
    pos1: Vec2<N>, 
    force_buffer: &mut Vec2<N>, 
    pos2: Vec2<N>, 
    closest: N, 
    mag: N
) -> Result<(), ErrTooClose>

Repel one object by simply not calling add_force on the other.