Rough cut of 'open-ils.acq.lineitem.cancel', which "Cancels a lineitem, any of its...

Rough cut of 'open-ils.acq.lineitem.cancel', which "Cancels a lineitem, any of its detail entries and corresponding copies and call numbers, and potentially related holds (if the bib becomes empty)."  Need to smoke test it, add hold deletion if the bib becomes empty (and add an org unit setting for optionally deleting the bib as well), and check to see if volume deletion is being handled automatically by open-ils.cat.asset.copy.fleshed.batch.update

From my open-ils.acq.lineitem.cancel branch

git-svn-id: svn://svn.open-ils.org/ILS/trunk@16076 dcc99617-32d9-48b4-a31d-7c20da2025e4