Bug 17843: Replace C4::Koha::getitemtypeinfo with Koha::ItemTypes

Bug 17843: Replace C4::Koha::getitemtypeinfo with Koha::ItemTypes

The C4::Koha::getitemtypeinfo subroutine did the almost same job as
GetItemTypes. On top of that it returned the imageurl value processed by
C4::Koha::getitemtypeimagelocation.
This value is only used from the 2 [opac-]shelves.pl scripts. Then it's
better not retrieve it only when we need it.

Test plan:
Play with the different scripts touched by this patch and focus on item
types. The same description as prior to this patch must be displayed.
Note that sometimes it is not the translated description which is
displayed, but that should be fixed on another bug report. Indeed we do
not expect this patch to change any behaviors.

Signed-off-by: Lari Taskula <lari.taskula@jns.fi>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>