Use sitemap.xml?page=x for sitemap chunks instead of sitemap-x.xml

Currently if you have multiple chunks in a sitemap, you currently get sitemap pages like these:
http://example.com/sitemap.xml
http://example.com/sitemap-1.xml
http://example.com/sitemap-2.xml

Note we can't do thing like http://example.com/sitemap.xml/1, etc since as per the specification, links in a sitemap page must not be *above* the location of the sitemap they're in.

Because of this we also have to have special menu items for *each* and *every* sitemap chunk:

  $items['sitemap.xml'] = array(
    'page callback' => 'xmlsitemap_output_chunk',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
    'file' => 'xmlsitemap.pages.inc',
  );
  $chunks = xmlsitemap_get_chunk_count();
  if ($chunks > 1) {
    for ($i = 1; $i <= $chunks; $i++) {
      $items['sitemap-' . $i . '.xml'] = array(
        'page callback' => 'xmlsitemap_output_chunk',
        'page arguments' => array((string) $i),
        'access arguments' => array('access content'),
        'type' => MENU_CALLBACK,
        'file' => 'xmlsitemap.pages.inc',
      );
    }
  }

I'm not sure why I didn't think of this before, but I'm not sure why we can't just use a 'page' query parameter like this:
http://example.com/sitemap.xml
http://example.com/sitemap.xml?page=1
http://example.com/sitemap.xml?page=2

Pros:
- We only need one default menu item to cover all possible sitemap pages.
- We don't need to run a menu rebuild whenever the number of sitemap pages changes.
- Flexible for changes if we need multiple contexts like languages/domains

Cons:
- Not exactly sure if it would be compatible with search engines, but I can't find anything to say it wouldn't.