Bug 797584 - New-owner - bill amount field links to wrong account

Amounts formerly linked to the 'transfer' split which is not reliably
determined. Link to the APAR split instead.

Note whereby a payment spans multiple invoices, it'll link to the
first APAR payment split.

gnucash/report/business-reports/new-owner-report.scm

@@ -745,7 +745,7 @@
            (and (< orig-value 0) orig-value)
            (and (>= orig-value 0) orig-value)
            (invoice->sale invoice) (invoice->tax invoice)
-           (txn->transfer-split txn)
+           split
            link-option
            (cond
             ((and (txn-is-invoice? txn) (eq? link-option 'simple))