Required for SIP checkin implementation, but also for internal correctness.
AddReturn had too many things going on, with no guarantee of data being
available for the later calls. At some point we started tacking on all the
branch transfer logic without testing edge cases. In particular, $borrower
is not checked to be sure it is defined, considering the item may not have been
checked out so no borrower would be associated. That means that CircControl
of "PatronLibrary" would be inaccurate, Circ Alerts will be totally confused
(untargeted), and the Fix... subs would fail.
Note that *many* errors are still present in _FixAccountForLostAndReturned, including
those where comments are added, such that it might behave strangely even with $borrower.
Renamed the internal subs with leading underscore, per convention. Changed
the arguments to be scalars when only scalars are needed, not entire objects.
Added depth to WrongBranch message that includes Rightbranch.