Merge the branch words-sections-deniskup

This commit merges the branch words-sections-deniskup. It was
originally merged to master, but without --squash, which this commit
contains.  This branch only contains fixes to handling of text
sections and no other things, in particular nothing to do with the
text outliner which will be merged to master during the merge window.

I have looked through all the changes line by line and I *think* that
I have checked everything.  I could find no new strings but I may have
missed something.  There are a number of new translations of old ones
because the branch has gotten master merged into it at some points.
Because of the freeze there should be no other new features but also
that could have slipped through my checks. If so, I hope that I can be
forgiven for missing it.

Conflicts:
	krita/integration/thumbnail/kritaanimation_kranim_thumbnail.desktop
	krita/plugins/extensions/dockers/animator/krita_animator.desktop
	krita/plugins/formats/kranimseq/kranimseq_export.desktop