Bug 7609: Improving links to find analytics and volumes when using UseControlnumber...

Bug 7609: Improving links to find analytics and volumes when using UseControlnumber (MARC21)

To test:
- switch on UseControlnumber
- add a serial record with 001
  - ldr pos 19 = a or
  - 008 (continuing resource), pos 21 = m
- add 2 analytics with with $w subfields containing the 001 of the serial
  - one with ldr pos 7 = a
  - one with ldr pos 7 = b
- add 1-2 monographical records linked to the serial
  - 8xx $w subfield containing the 001 of the serial
  - 490

The serial should show 2 links (in both OPAC and Intranet):
'Show volumes' should only bring up the monographical records.
'Show analytics' should only find the analytical records.

Without the patch both links would find all linked records, no difference
between both links.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>