Bug 13001: Refactor VAT and price calculation - parcel page

Bug 13001: Refactor VAT and price calculation - parcel page

Bug 12969 introduces a subroutine to centralize VAT and prices
calculation.
It should be use in the acqui/parcel.pl script.

Test plan:
1/ Create 4 suppliers with the different configurations
2/ Create a basket and create several orders
3/ Go on the parcel page
4/ You should see, on the "pending orders" table, the same prices as
before this patch.
Note that the prices are now correctly formated.

You could see one change for the supplier configuration 3 (1 0):
If the cost of the item is 82, discount 10% and vat 5%:
The "Order cost" = 140.58 instead of 140.57.
Indeed, before this patch, the order cost was wrong, now you should have
70.29*2 = 140.58

( before: 140.58 + 7.03 = 147.61
  now:    140.58 + 7.02 = 147.60 )

5/ Receive the items and return on the parcel page
Now the "Already received" table with the same prices as before this
patch.
Note some differences too:
- There was a td tag missing, the table was badly formated, it's now
fixed (column below the "Cancel receipt" link).
- The prices are now correctly formated.
- For the configuration 2 (1 1), if the cost of the item is 82, discount
  10% and vat 5%:

( before: 140.57 + 7.03 = 147.60
  now:    140.58 + 7.02 = 147.60 )

Note that 7.03 is the "correct" value, but on all other pages, 7.02 is
displayed.
To be consistent, we should display the same prices everywhere.

Signed-off-by: Paola Rossi <paola.rossi@cineca.it>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>