[IMP] product: search on internal reference

When searching on the name of a product.template, search also on the default_code. Move the filter from product.product to product.template.
The field default_code is on the product.product but accessible through a related field, meaning when reading it will fetch only the first variant but searching on all variants.
Fixes #3399
[IMP] stock: display chained moves

Add field move_dest_id in stock.move form view for better debugging of complexe stock flows.
[IMP] point_of_sale: distinguish discounted lines

After closing a POS session, the pos order lines are grouped by product.
Instead, distinguish products with a different discount notice to have different lines for such products in the generated account.move for better traceability.
[FIX] fix a crash with create popup forms (web client)

it was trying to call the forme 'hide' method on the searchview.  To
solve the problem, I readded the method (and renamed it to do_hide for
consistency with views)
[MIGRATED] website_forum: migrated website_forum into new api + solved some bugs
[IMP] website_forum: removed unnecessary imports
[IMP] website_forum: improved badges access for anonymous user
[IMP][webiste_forum] improved functions, replaced most of api.one with multi, solved some bugs
[IMP+FIX][website_forum] fixed issue of assets, removed all karma releted fields
[REVIEW] Reviewed code.