[IMP] Rounding should be done on move immediately to default UoM and quants should...

[IMP] Rounding should be done on move immediately to default UoM and quants should be rounded to the default UoM + remaining_qty

[FIX] Remaining qty should each time be in the default UoM of the product

Even with different UoM we want a consistent matching between moves and pack operations.
When calculating the remaining qty on move/pack operation we always start by converting the
qty on the move/operation to the default UoM and afterwards we subtract the links between them
which will also be in the default UoM of the product.
In order to create backorders / extra moves these quantities are used.