Batch importer plug-ins should handle lack of USE permission better

[Nicklas Nordborg]

The current implementation of the batch importer simply ignores all items that the logged in user doesn't have permission to use. The result is that this is reported as an ItemNotFoundException which may be confusing because if the user has READ permission it is visible in listings and other places.

It would be better if the items were loaded and the permission checked. An error handling option to handle this must be added with the same options as for the item-not-found case.

In addition, the code that handles multiple found items should be able to handle the case were only one of the items found can be used. This case should transparently be transformed into the single-item-found case.

[Martin Svensson]

(In [4595]) Fixes #1142 Batch importer plug-ins should handle lack of USE permission better.

[Martin Svensson]

There are two more cases where the permission handling can be improved.

[Martin Svensson]

(In [4597]) Fixes #1142 Lack of permission when trying to write to an item or use a reference is now handled. The last case covers also when an array slide is used by another hyb.