Function vec4::lerp

pub fn lerp<'a, T, F>(
    out: &'a mut [T; 4], 
    a: &[T; 4], 
    b: &[T; 4], 
    t: F
) -> &'a mut [T; 4] where
    T: Copy + Num + Cast<F>,
    F: Copy + Num + Cast<T>,