minidom: Use NSChoice in more places
It changes Element::{get_child,get_child_mut,has_child,remove_child} to also accept NSChoice. In order to do that, it changes the Vec in NSChoice to a slice reference and mark it Copy.
It changes Element::{get_child,get_child_mut,has_child,remove_child} to also accept NSChoice. In order to do that, it changes the Vec in NSChoice to a slice reference and mark it Copy.