Returns reworking to handle empty GetItemIssue

Returns reworking to handle empty GetItemIssue

Code cannot rely on issueinformation being populated.

Note there is room for better efficiency to have AddReturn also provide the
itemnumber (where existing) so that GetItemnumberFromBarcode is not called
at both levels.  Unfortunately there is discrepancy between this idea (for
efficiency) and the stated purpose of the $iteminformation object returned,
since $iteminformation is specifically the info from the issues table and
MUST be empty when the item was not in fact issued.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>