Add machinery for attributing debits to funding source credits,

Add machinery for attributing debits to funding source credits,
and thereby to funding sources.

1. New table, acq.debit_attribution.

2. Create three new types, to be used internally by:

3. New function acq.attribute_debits().

M    Open-ILS/src/sql/Pg/200.schema.acq.sql
M    Open-ILS/src/sql/Pg/002.schema.config.sql
A    Open-ILS/src/sql/Pg/upgrade/0143.schema.debit_attribution.sql
M    Open-ILS/examples/fm_IDL.xml

git-svn-id: svn://svn.open-ils.org/ILS/trunk@15398 dcc99617-32d9-48b4-a31d-7c20da2025e4