Users are no longer expected to manually set the status of an expense
and, instead, have to add payments to such expense to mark it as partial
or paid.
That means that the PL/pgSQL functions must not accept a status
parameter, the edit and new forms should no longer have a field for
the status, and that the expense list should no longer have the “quick
edit” for their status. That’s why it no longer should have a pointer
cursor, unlike invoice or quote status.
We only want two statuses for expense: not yet paid (pending), and paid.
Thus, it is a bit different from quotes and invoices, because expenses
do not pass throw the “workflow” of created→sent→{pending,paid}. That’s
way in this case the status field is already in the new expense form,
instead of hidden, and by pending is not equivalent to created but
unpaid (i.e., the same status color).
With the new select field in the form, the file field no longer can
span two columns or it would be alone on the next row.
Closes#67.