Function try_quad_normal 

pub fn try_quad_normal<T: FloatScalar>(
    v0: &Vector3<T>,
    v1: &Vector3<T>,
    v2: &Vector3<T>,
    v3: &Vector3<T>,
    epsilon: T,
) -> Option<Vector3<T>>

Computes the normal vector of a quadrilateral.

Returns None if the quad diagonals are too small or parallel.