Bug 16519: Replace 'our' with 'my' in [opac-]addbybiblionumbers.pl

Bug 16519: Replace 'our' with 'my' in [opac-]addbybiblionumbers.pl

To avoid bug like bug 16518 and to ease the readability/maintainability
of these scripts, this patch replaces the use of 'our' with 'my' to
avoid the use of global variables.

Basically the code has been moved from subroutines to the appropriate places.

Test plan:
At the intranet and OPAC sides
1/ Add items to a list
2/ Add items to a list using an existing name
3/ Add items to a list you don't have right on it (by modifying the
biblionumber in the url)
4/ At the OPAC, use the opac-addbybiblionumber.pl without being logged
in to add items to a list

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer  <katrin.fischer@bsz-bw.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>