Enable split & defer for invoice line
remove another way of solving divergences
remove "quiet" from testInvoice
testInvoice: Use new way of split & defer

This shows new problems. The splitted movement have an accepted quantity of 0,
so nothing is expanded below, and no accounting is built. This is the cause of
test_13_SplitAndDeferInvoice failure.
Also, existing applied rules cannot be expanded anymore because they try to
generate a profit & loss movement.