I should be able to open an external page in the same tab

(User Story, Closed -> Fixed, Priority: Critical, Test Status: Unit tested , Reported By Justin du Coeur, )

Summary: That is, there are occasions where I want to be able to federate a Querki Space with an external site relatively tightly, and therefore links to that site should not open a new tab.

Requested by Xavid for the GBLS Space, but there are no doubt more use cases for this.

We probably shouldn't encourage this usage too much -- in most cases, it's appropriate to stay local. But we should come up with a way to be able to do it.

What is the syntax for this? How do I specify such a link? This needs some thought and design.