I’ve removed the total amount because it is very difficult to get it
with pagination, and customer never saw it (it was from Numerus), thus
they won’t miss it—i hope.
Copied as much as i could from Numerus, and made as few modifications as
i could to adapt to this code base; it is, quite frankly, a piece of
shit.
We need to be able to create invoices from scratch “just in case”,
apparently, but it is not yet possible to create an invoice from a
booking.