[FIX] website_sale: Postal Code is required during checkout for countries without postal codes; Zip must be not required.
[FIX] product: is_product_variant is all time false. result: can not change ean because the field is hidden in the view. Need to overwrite the function field on product.product to have the real value (true for product.product)
[FIX] website: update jQuery.transfo lib + adapt code
[FIX] website_sale_options: only one optional product is added to the cart and the quantity of the optional product don't change in the cart when we click on more or less. Fix the number of items displayed in the modal options.
[FIX] account.fiscal.position: Fix get_fiscal_position for auto apply:

First match a fiscal position for the given country, then for a country
group containing the country. If none found, search a fiscal position
without country nor country group
[FIX] website.sale: Double / triple digits do not get displayed correctly on ecommerce quantity selector
[FIX] avoid leaving dangling account moves when deleting a bank statement

Fixes #3292