[accounting] New API migration - WORK IN PROGRESS

- Task: https://www.odoo.com/web/#id=9955&view_type=form&model=project.task&action=333&active_id=131
- Pad: https://pad.odoo.com/p/r.Uy4wEA7I4G4GwPaU
i don't get the meaning of this comment. 

BTW, I think, it's a good occasion to get rid of the subfolder 'project' in account module that is confusing and not following the usual module structure. Please make one .py file under account that holds all the classes related to analytic.