preperation to 4.4 release-notes

* Must of version number in .rst files replaced by |release| and |version| variables.
* starting preperation for 4.4 release-note.

also, could it be possible to cherrypit: e016d570eb5359f5a6432b87312ef6725c00354b into 4.3 branch to fix ubuntu packages in the upgrade instructions.

thank you.