Address LP #983487: Avoid clobbering bib records at authority merge

Address LP #983487: Avoid clobbering bib records at authority merge

If you've set up a relationship between bib record and authority records
based on arbitrary sets of controlling and controlled fields, but your
authority records don't have the right Subj fixed field value
corresponding to a control set that defines the controlling and
controlled fields you're using, authority merge operations may wipe out
lots of bib data.

Yamil Suarez encountered this bug in testing, and in his case what he
needed to do was set the Subj fixed field in his authority records to
'A' to match his Song Title Index (see the launchpad bug referened
above).

Previously, you could not actually save the Subj fixed field in the MARC
editor (which showed HeadSubj instead of Subj for authority records, and
didn't work).  Now you can.

Thanks to Mike Rylander for help in figuring out the above.

To provide additional protection against merging authority records when
they might not be linked with the right control set, the Manage
Authorities interface will now also show you the linked control set for
any given records.

The implementation of that last bit incidentally meant making sure flesh
and flesh_fields get passed through to PermaCrud for retrieve() calls via
the Javascript openils.PermaCrud wrapper.

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>