Bug 11592: Applying filtering to opac interface.

Bug 11592: Applying filtering to opac interface.

Applying the filtering and then...
Debugging opac/opac-detail.pl filtering
Debugging opac/opac-ISBDdetail.pl more
Debugging opac/opac-export.pl
Tweak opac/opac-export.pl fix variable declarations, conditional assignments
Debugging opac/opac-showmarc.pl

https://bugs.koha-community.org/show_bug.cgi?id=11592

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>