Bug 10841: Make edit/delete item context links in cataloguing translatable

Bug 10841: Make edit/delete item context links in cataloguing translatable

HTML created with Javascript is not translatable the way HTML is
normally translated. _() syntax has to be used to have strings
translatable.

To test:
- Edit items for a record with multiple items
- Click somewhere in the items table
- Verify the links for editing and deleting items show up and work correctly
- Apply patch
- Verify the links still show the same behaviour

Bonus:
- Run 'perl translate update <languagecode>' in misc/translator
- Verify that Edit item and Delete item show up in the po file, translate them
- Install updated po files running 'perl translate install <languagecode>'
- Verify links show up translated and work correctly

Patch also fixes capitalization for a couple of error messages - only change
there is: Deleted > deleted.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>