increase fieds size of ref supplier (order and bill)

increase ref fields size (like customers facture)

extend ref fields size (like for customer commande)

increase size of ref supplier (some supplier are very long ref...)

notifications

to avoid future bugs.

New: Add missing trigger PROPAL_CLASSIFYBILLED.

EMail use now language of target contact.
Can also define a fixed email for notifications.
Better error management

Transifex sync

Migration SQL could not insert accounting records because datec was set
to NOT NULL

background (nearest bootstrap). Remove image background.