* This commit adds an easy access to products and variants from the app switcher / root menu, similar to what exists for contacts.
* Move an action to view stockable products to stock, as it is only executed from stock.
- Add an option in the General Settings : Use product variant.
- If this option is disabled : don't show any reference to variants
- When going on the product template view, and clinking on the stat button under the tab Variants,
the form view should display only the information related to the variant
- Fields moves from product_template to product_product : weight, volume, cost price,
- DO NOT display these fields on the product_template if there are more than 1 variants.
- In product variant view, set some fields readonly and add a link to edit it from Template.
The rules 'base.res_partner_rule' and 'product.product_comp_rule' are now inactive by default. This will make these models visible for all companies defined in the database, ignoring the configuration of companies set on product and partners.