Bug 10345: Increment copy number when adding multiple copies.

Bug 10345: Increment copy number when adding multiple copies.

To test:
1. Add multiple copies of an item with data in the 'Copy number' field. Note that tha data will be identical for all items.
2. Apply patch.
3. Add multiple copies of an item with a positive integer (ie. only digits) in the 'Copy number' field. Note that the copy number is incremented for each item.
4. Add multiple copies of an item with some other type of data in the 'Copy number' field. Note that the copy number field remains unchanged for the added items.

Signed-off-by: Pierre-Marc Thibault <pierre-marc.thibault@inLibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>