Changes to "schema" aka "color theme" handling

[Christoph Cullmann]

KTextEditor uses since long the KSyntaxHighlighting framework to provide 
the highlighting instead it's old own code.

But for the coloring, we bypassed all stuff provided by this framework.

For the frameworks release in October I want to change this and switch 
over to the color themes as provided by KSyntaxHighlighting (but still 
allow to configure them like now via the GUI and provide own ones in the 
"old" style).

The matching merge request is:

https://invent.kde.org/frameworks/ktexteditor/-/merge_requests/20

If you have some time to test this, feel welcome!

Beside that, it would make sense to provide some more bundled themes (if 
available as MIT licensed stuff), see this development issue for some 
potential candidates:

https://invent.kde.org/frameworks/syntax-highlighting/-/issues/2

Contributors welcome ;=)

The stuff must end up as JSON file in 
https://invent.kde.org/frameworks/syntax-highlighting/-/tree/master/data/themes

kate-editor.org will provide some auto-generated overview with example 
renderings, like we do already for the syntax highlightings:

https://kate-editor.org/themes/

(that stuff is generated via 
'https://invent.kde.org/frameworks/syntax-highlighting/-/blob/master/data/generators/update-kate-editor-org.pl', 
improvements welcome, too)

Greetings
Christoph

-- 
Ignorance is bliss...
https://cullmann.io | https://kate-editor.org