reconcile_partial() return reconcile record id

It should be similar like it's done with reconcile(). That would help a lot when needs to make automatic partial reconciliations.
Merge pull request #633 from komsas/patch-1

account: Unify reconcile_partial and reconcile behaviour: return the account.move.reconcile id
[FIX] product and pricelists

1.) remove cost price option based on pricelist
2.) merge cost price and supplier section on product or cost price based on pricelist.
3.) improve tooltip of base field in product pricelist items.