Settings needs to make category rdfs:subClassOf its classification

[josephguillaume]

Tableview columns appear blank for custom classifications created with settings.
This can be fixed manually by adding rdfs:subClassOf definitions, e.g.

:id1625386228650 rdfs:subClassOf :id1625386215075.
:id1625386377799 rdfs:subClassOf :id1625386215075.

where settings had created:

:id1625386215075
    rdfs:label "Task categories";
    owl:disjointUnionOf
    ( :id1625386228650 :id1625386377799).

This is necessary because renderTable queries for rdfs:subClassOf, not owl:disjointUnionOf:
https://github.com/solid/issue-pane/blob/a213104dfb997a4592f5ff3fe82c2cc6d85a5f8c/issuePane.js#L275-L279

Presumably the fix will involve adding a statement to trackerSettingsForm.ttl, probably in core:CategoryForm
https://github.com/solid/issue-pane/blob/a213104dfb997a4592f5ff3fe82c2cc6d85a5f8c/trackerSettingsForm.ttl#L97-L116

However, I'm not yet sure how solid-ui would specify this, and a similar problem has already been raised for states (issue #22), which are optionally specified as rdfs:subClassOf wf:Open

[josephguillaume]

The function fixSubClasses seems to also be tackling this issue but currently raises an alert with code to update the doc commented out:
https://github.com/solid/issue-pane/blob/a213104dfb997a4592f5ff3fe82c2cc6d85a5f8c/issuePane.js#L173-L177