Simplify contact / addresses management. Contact now use the same
address as their parent. Invoice, delivery and other contacts
have their own address. Default contact is removed; the default
is now contact.
As contact automatically use the company address, and other types
use their own, use_parent_address field is removed, leading to
some simplification in the address management.
Also add company_type field, to have a selection field instead of a
boolean one when display company / person choice. This is an interface
field build on the is_company field, to create the minimum change
and avoid disturbing the logic based on is_company. When migrating
to the new API, its implementation will be cleaned.
Thibault Delavallée