Miscellaneous updates:
- Strip caption text (sometimes leading spaces)
- Updated test HTML so it has data-mw-footnote-number attributes that were released in October 2025 and are a more reliable approach for detecting references (IDs are tricky).
- Updated test HTML now missing key image so added another set of media tests from a different example.
- Allow messagebox divs (not just tables) - see #132
Minor error catching improvements Fix element identification logic to handle expanded element definitions