made backdating smarter by using the circ interval and parsing the backdate

made backdating smarter by using the circ interval and parsing the backdate
as an ISO time so we get timezones and not just YYYY-MM-DD

ported claims-returned and lost code to CStoreEditor, made everything run
inside the same transaction to prevent bugs with leaving transactions closed
when they should be re-opened (among other things)

mark-lost now supports org settings at any level in the tree
new settings are whether to apply default item price on price==0 vs. price==null

git-svn-id: svn://svn.open-ils.org/ILS/trunk@7130 dcc99617-32d9-48b4-a31d-7c20da2025e4