MO : Deduction of amount already paid

[timactive]

Questions	Answers
Branch?	develop
Description?	An order can have other payment on the same order process we can have a payment that is made before (eg payment by gift card or balance / have), so it is necessary to deduct the amount that has already been paid. This update have visual impact for the final customer. I regularly implement this update near my clients.
Maybe one day we will be able to make multiple payments, this update is a first step :-).
Type?	Feature
Category?	MO
BC breaks?	no
Deprecations?	no
Fixed ticket?	no
How to test?	Paid with bank wire and check if amount is good.