Ability to export subset of project

[reckart]

It would be nice if there was an easier way to export data formats like CAS XMI 1.1 for further processing, especially choosing only a subset of all the documents in the project to be exported.

I was initially looking for an export option in the monitoring windows. As this one already has options to choose subsets of document by status, editor, etc, I think this would be the perfect place to enable a subset download.