Make highlightjs theme configurable

[nkoehring]

Building on top of #31 this adds an option to the config.ini that allows to set a global theme.

pros

• Allows instances to change the highlightjs theme to their wishes.
• Works fine for single user instances.

cons

• Admins need to download the themes first. Maybe use a CDN URL instead of a local one?
• Setting is global for all users.

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[thebaer]

Thanks for submitting this, @nkoehring! And sorry for the delayed response.

I think it'd be great to allow customization here, but it is tough for multi-user instances -- ideally we'd have something that each user can set themselves, just like they can modify their own CSS.

There's a backend mechanism for handling per-user settings right now that we could use: the userattributes database table. But we'd need to add the user interface for updating their preferred style. And ideally, we'd incorporate these styles locally -- a few options:

• By default, include several other themes to choose from locally, or
• Provide a way to automatically download and install themes

[nkoehring]

Yes, as mentioned I see the problematic that it only works on a global level. I proposed it as a "better than nothing" version and actually patched my own running instance with it. To provide it on a per user level would be much better obviously.

As a good middle way, and because themes are simply CSS, how about using a CDN and simply download them on the fly by inserting a tag?

[thebaer]

Yep, that'd be great if we could download new themes on the fly.

[thebaer]

With some more thought, I think the best way to do this would be to include it in the collectionattributes database table. That way, whether you have a single user or multi user instance, everything works correctly.

Since this will take a little more time, and potentially a different path to get there, I think we should avoid adding config options that might disappear at some point and close this for now. If you'd like to submit a permanent solution at some point that works across single- and multi-user instances, please feel free!