external links are opened in same tab in document editor

1) In the browse perspective, open a document with external links and don't start editing the document.
2) Click on an external link

You'll notice that the link opens in the same tab. For the channel manager we implemented the behavior that external links are opened in a separate tab (see related issues).

Also in the browse perspective, implement a similar check and message. The channel manager shows a JavaScript popup with the following text

This external link will be opened in a new tab.
Do you want to continue?

<ok> <cancel>