Add picture keyword to comment export.
Short, concise description of the idea
Provide a way for comment exporting to get picture keyword information.
Full description of the idea
Include 'picture_keyword' as one of the 'property' values returned by export_comments.bml.
- Clients and backup software could get the picture_keyword without scraping HTML.
- I can't think of any. 'property' is optional, and this would also be optional, so older clients that don't check for it wouldn't know it was there.