Simplify low level wrapper

Please don't do this kind of checks on the low level warpper, checking for dims and raising exceptions should be done on the pure python side.

#[pymethods]
impl Vector {
    #[new]
    fn new(obj: &PyRawObject, in_array: Vec<f64>) {
        if in_array.len() != 3 {
            // TODO: raise an exception
            panic!("Wrong number of rows");
        }
        let mut tmp_vector = KdlVector::zeros();
        for i in 0..in_array.len() {
            tmp_vector[i] = in_array[i];
        }
        obj.init(Self { vector: tmp_vector });
    }
}