Bug 12987: Update table footer with the visible rows

Bug 12987: Update table footer with the visible rows

This patch is the preparation step for others.

On acqui/acqui-home.pl and admin/aqbudgets.pl, it will be possible to
see the totals in the footer updated with the filtered rows.

Test plan:
This cannot be tested alone, you have to apply it with others (see the
"Blocked" bug reports).

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>