Specification Manager should allow specifying packages

[PeterHeintz]

As any other element packages are capable to hold notes. These notes can e.g. hold information, providing some information what the content of the package is, background information or any other information which is regarded as useful.
The Specification Manager is a good feature to edit and view notes of several elements, however packages are filtered out.
Please allow to show and use packages in the Specification Manager as well.