FIX :[bug #1309]
Keep value on validtions failure
fix can't add line with product in supplier order
Merge pull request #1502 from FHenry/3.5

 Fix restrictedearea bug & delete extrafield on delete invoice
Merge pull request #1508 from KreizIT/3.5

FIX :[bug #1309]
Merge pull request #1512 from atm-alexis/3.5

fix can't add line with product in supplier order