[IMP] stock: when checking the state of the product, do not recompute the quantity on every move but only the one currently browsing (optiomisation)
[FIX] ir_cron: use the same search criteria as when listing job to excecyte when acquiring the ock on the job before its execution to prevent running already executed job

Backport of fix made in trunk
[FIX] orm: do not resize unlimited char fields