Screenshots and videos for the 2.9 release

[Boudewijn Rempt]

Hi!

We're working on the release notes, announcement and pdf and we need a bit 
of help. We need extra videos and screenshots for:

Videos

* Liquify
* HDR painting (Wolthera is going to have a try tonight, so this isn't 
urgent)

Screenshots

* MDI Screenshot: we propose to use krita_texture_bg.jpg, by Deevad, but 
maybe we can figure out a better one?
* Liquify
* Technical art and linework (the new line tool and assistants)
* coloring linework

Boudewijn