Add Schema.org support via JSON-LD

[krabina]

Feature request

This has been discussed here.
SMT would probably a good place to implement something like this. Instead of "only" meta-tags, a JSON-LD representation that can be customized/populated from semantic properties would be a very valuable addition to any SMW instance.

[krabina]

There might be some ideas/code that can be taken from here
https://github.com/octfx/wiki-seo/blob/master/includes/Generator/Plugins/SchemaOrg.php

[krabina]

This feature has been implemented in the Page Properties extension

[krabina]

See #80