Go back to existing tab instead of opening new one if document already open

[bosschaert]

Selecting a document in the browse view always opens a new tab with that document, even if the document was already opened before.
We should go back to an existing tab with the previously opened document if it's already there to avoid multiple open tabs on the same document.

Steps to Reproduce

1. Go to the browse view
2. Create a new document foo - this opens a tab with the foo document
3. Go back to the browse view, ensuring that the foo document is still open
4. Open the foo document

After step 4 you'll have 2 tabs with the foo document. It would be better to have jumped back to the already open tab for it.