point_of_sale: Add _prepare_analytic_account method to easily set analytic account from custom module
[FIX] web: t-attf expects #{} or {{}} for variables

not just {}. Nevertheless, It somehow worked in Odoo 7.0 and saas-3.
[FIX] website: main layout - title more flexible for customization. (additionnal_)title was overwritted by website_meta_title or main_object.name
Merge pull request #3332 from akretion/8.0-prepare-analytic-pos

point_of_sale: Add _prepare_analytic_account method