This is to handle refunds, which are invoices with negative amounts,
that can be both issued or received (i.e., an “expense”).
The API provided by PostgreSQL is mostly the same, and internally it
deals with negatives, so the Go package only had to change selects of
collection.
This actually should be the “payments and receivables” section, however
this is quite a mouthful; a “receivable” is a payment made **to** you,
therefore “payments” is ok.
In fact, there is still no receivables in there, as they should be in
a separate relation, to constraint them to invoices instead of expenses.
It will be done in a separate commit.
Since this section will be, in a sense, sort of simplified accounting,
i needed to introduce the “payment account” concept. There is no way,
yet, for users to add them, because i have to revamp the “tax details”
section, but this commit started to grow too big already.
The same reasoning for the attachment payment slips as PDF to payment:
something i have to add, but not yet in this commit.
jordi fita mas