Links redirect to Lemmy-UI

[Neriderc]

When an instance is running mlmym as an alternate frontend, links to posts on the instance will redirect to the main lemmy-ui frontend.

As an example, Lemmy.nz has a tagline set with links to rules, FAQ, etc. On the mlmym alternate frontend at https://old.lemmy.nz, the links appear above the feed, but clicking them will redirect the user to the https://lemmy.nz hostname running the lemmy-ui frontend.

I think this might be related to #101. Might also be related to #7.