A **product set** is a list of products which end customers aren't aware, this
list is defined by sales manager.

This module aims to help salesman to quickly create several sale order lines
at once in a quotation.

After a *product set* is added to the sale order, each line can be updated or
removed as any other sale order lines.

This differs from packing products as you don't follow *product set*
are not linked to sale order lines once they are added.
