LP#1686194 Account for adjustments when generating fines

LP#1686194 Account for adjustments when generating fines

Fine generation stops at a predetermined 'max fines' amount, but this
does not account for possible adjustments which lower the effective
fine amount.  This situation is common in cases where lost items are
returned, and the library wants to generate additional overdues upon
that event.

With this commit, fine generation will pull in any adjustments applied
to overdue fines, and use those to offset the current total fine when
checking for max fines.

Also includes test for this condition.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Jeff Davis <jdavis@sitka.bclibraries.ca>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>