Bug 26755: Make the guarantor search popup taller

Bug 26755: Make the guarantor search popup taller

This patch changes the dimensions of the popup window in which
guarantors are chosen during the patron edit process.

The patch also removes an obsolete function delcaration for "Dopop"
which is unused.

To test, apply the patch and open a "child" type patron account for
editing.

Click the "Add guarantor" button. This should trigger a popup window.
Eyeball the size of the window, you'll be able to tell that it is
exactly 800 pixels wide.

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>