Allow propagation of encumbrances without funds

Allow propagation of encumbrances without funds

Some libraries must return all unspent money to some funding agencies at the
end of the year.  To support this, we give the year-end close-out operation
the ability to dump the money from rollover-enabled funds into the void. Funds
are still created for the next year, and encumbrances are moved to theses
analogous funds.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Bill Erickson <berick@esilibrary.com>