Remove Jeff's org_unit settings for using forgive payments instead of voids.

Remove Jeff's org_unit settings for using forgive payments instead of voids.

Remove string constants for Jeff's new org_unit settings.

IDL changes to add void_payment.

Add the money.void_payment table in the database.

Remove voided, voider, and void_time columns from money.billing tables.

Remove voided, void_time, and voider field from money::billing in IDL.

Update money.materialized_billable_xact_summary in upgrade script.

Modifications to void_overdues to make void payments.

Reuse and update Jeff's outstanding outstanding_bills_for_circ() method.

Rename outstanding_bills_for_circ() to outstanding_bills_for_xact(),
because it really is that generic.

Modify void_billing in O::A::Circ::Money to use the new void payment.

Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>