- Display mirror domain instead of an arbitrary index (which could change)
- Fix showing 404 page for non-existent mirror redirection links
- Move default mirror definition into downloads.py for easy changing
Initially the rel="alternate" hreflang="xx" links in the sitemap caused the
size of the file to increase exponentially as additional languages were added.
The current implementation has a single sitemap.xml for each language, with a
sitemap_index.xml at the root.