Maxi debug of multiprice feature

ChangeLog

build/exe/doliwamp/doliwamp.iss

htdocs/admin/produit.php

htdocs/comm/addpropal.php

htdocs/comm/multiprix.php

htdocs/comm/propal.php

htdocs/commande/commande.class.php

htdocs/commande/fiche.php

htdocs/compta/facture.php

htdocs/contrat/fiche.php

htdocs/facture.class.php

htdocs/install/inc.php

htdocs/master.inc.php

htdocs/product/fiche.php

htdocs/propal.class.php

htdocs/societe.class.php