Issue: Display main article image as page icon

Admins can set the default thumb size already for the "thumb" attribute on the IMAGE/FILE BB-Code. If this size is not sufficient, the wiki is designed to automatically generate other thumb sizes based on an admin setting (which doesn't exist yet). Other requested sizes are supposed to go into a special "moderation" queue on a per-use basis (this queue also doesn't exist yet).

In order to achieve a thumbnail of a "main" image, however, there first needs to be a way to define a "main" image without having to actually parse the page.

Indeed. Often the main image of a wiki is in the info box.
so maybe it's best to create this functionality together with the info box function.

I think that this function will greatly improve Vaultwiki in the sense that it will make Vaultwiki visually more appealing. Both to current VW customers as prospective customers.

As xenforo has put a high importance on images in its thread listings, its also logical that vaultwiki does the same.
Related suggestion: https://www.vaultwiki.org/issues/3663/

This is due in the next release. See the Image area, which now shows thumbnails of the images in the listings, or a file-type icon for non-image files if the file-type has an icon defined: https://www.vaultwiki.org/pages/Image

For regular pages, we are working on a field where you can pick a different Font Awesome icon, enter an image URL, or pick an image from VaultWiki's attachments. You can see this field applied to at least one article here: https://www.vaultwiki.org/demo?do=list

There are a lot of other places that this field needs to be used (feeds, link previews, sitemaps, etc), still working on that.

Image URL option works and proxies for external URLs.
Entering the name of a wiki attachment works.
Changes to the icon are tracked with new revisions.

Still need to make icon changes appear in the read-out for a revision (i.e. pegasus changed the icon).

Icons are used in feeds now (as well as other lists).
Icons are added to the main heading of wiki articles.

Should create a global setting to enable custom icons, as well as an area setting. It should be possible to set which options are available for icons (Font Awesome, URL, attachment).

Still need to create the select for Font Awesome characters, use the icon in previews and sitemap. After the templates are updated for all platforms, need to work on Javascript enhancements for the editor field:

• Icon preview should update automatically if the selection is changed.
• Should be possible to use the attachment chooser to pick a wiki attachment.

Marked as implemented in the next release. There are no Javascript enhancements for the editor field yet, but the function is still incredibly usable and useful. It is no more complicated than using the WIKI or IMG tags for image-based icons (enter wiki page name / image URL), and the select drop-down shows Font-Awesome characters.