[scribus] Thai support

[Václav Šmilauer]

> With the soon-to-be-official 1.5.3 version, we hope to be doing a better
> job with a number of languages, including some southeast Asian ones.
> At the same time, we want some feedback, hopefully as specific as
> possible, where there are problems.
Thanks. I am using trunk (the indigo-dock appimage, precisely), so those 
should be already in place. I think people having some knowledge about 
typography of those languages must comment, definitely not me :) Cheers, v.