Consider making some user content (e.g. text blocks) translatable

[LukasKalbertodt]

This came up during the summit. Some people would like to specify some parts of Tobira in multiple languages. For example, most installation will have a "welcome" text on the home page. Having this in multiple languages would be nice.

I think making text blocks and title blocks translatable shouldn't be that difficult. In the DB, we would just replace the text column with hstore. The block editor would need to be adjusted, which is probably where most of the time would be spent.

It would also be nice to be able to translate page names. Here again, we would only expect top level page names to be translated. Implementing this is a bit more tricky maybe, as our realm name system is already very complex, unfortunately. And realm names are stored in many places, including the search index. So changing this would require touching lots of places.