Signed-off-by: Maxime Gaillard <maxime@naeka.fr>

Conflicts:
	www/invoicing/api/doc.py
	www/invoicing/api/resources/embedded/invoice_item.py
	www/invoicing/models/embedded/invoice_revision.py

Improved HTML sanitizing

Support optional line items on quotations and purchase orders

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>

Added agreement line on quotations

Fix Export files reverse_delete_rule recursion (NULLIFY instead of DELETE)
Fix imports

- No more on the fly line item generation
- These documents line item is now flagged as "translatable" and is hold as-is with its translation context on the database

Fixed credit notes of down-payment invoices amounts

Fixed credit notes statistics creation
Fixed unicode username

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>