Bug 8037: (follow-up) bad sql query and variable renaming

Bug 8037: (follow-up) bad sql query and variable renaming

The first patch does a left join on aqorders_items which returns too
much order lines.

This patch follows the Galen's suggestion: it removes the join and calls
the GetItemnumbersFromOrder routine for retrieving itemnumbers.

Bonus: the "parcelitems" variable is badly named and obfuscates the code.
I changed it for "orders".

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>