Meta: CSV format and video fields

What's included

• CSV columns: id, title, description, link, image_link, price, sale_price, brand, mpn, gtin, additional_image_link (up to 15 images), availability, condition, item_group_id, shipping_weight, shipping, google_product_category, plus your additional fields.
• Fields that work only in one format are hidden for the other; a field saved earlier for another format shows a warning so you can remove it or switch the format.
• Meta XML price fix: g:price shows the compare-at price only when it is higher than the price, and g:sale_price is left out for products not on sale unless "Add Sale/Discount Price even though the product is not on sale" is checked.