Implement iterators for the array types about gdnative HOT 3 CLOSED

macro_rules! impl_iter {
    ($array_ty:ty, $element_ty:ty, $iter:ident) => (
        pub struct $iter<'a> {
            array: &'a $array_ty,
            index: i32,
            len: i32,
        }

        impl<'a> Iterator for $iter<'a> {
            type Item = $element_ty;

            fn next(&mut self) -> Option<Self::Item> {
                if self.index < self.len {
                    let ret = Some(self.array.get(self.index));
                    self.index += 1;
                    return ret;
                } else {
                    return None;
                }
            }

            fn size_hint(&self) -> (usize, Option<usize>) {
                (self.len as usize, Some(self.len as usize))
            }
        }

        impl<'a> IntoIterator for &'a $array_ty {
            type Item = $element_ty;
            type IntoIter = $iter<'a>;

            fn into_iter(self) -> $iter<'a> {
                let len = self.len();

                $iter {
                    array: self,
                    index: 0,
                    len
                }
            }
        }
    )
}