Editing a chess wiki I would like to edit wiki notes on chess, using a text editor that could interact with a program like xboard or similar (that is being able to enter moves and variations in the wiki by playing them from the board, for instance, and the other way round : click on moves in the text to see the position on the board).

The reason for this question is that scid, that I like a lot despite being a bit old-fashioned and buggy nowadays, has a very poor editor (no linking abilities, a pain to use). And xboard editor is even worse.

Of course, using latex could be an option, but it lacks the simplicity of a wiki, and I fail to see how to make a text editor interact with a xboard-like program.

It amazes me than no such a thing exists. The closest program I have seen is r/chess pgn viewer, but it does not seem under active development (not really an issue, but it is not clear to me how to use it for a private wiki). Any ideas ? 

Help will be much appreciated.
Have you tried one of the more recent forks of Scid?  Specifically ScidvsPC, which is actively maintained.  At the very least it reduces many of the bugs and there are some improvements.  The export to HTML function now includes a javascript option to produce a board viewer for websites, that might do some of what you want.  It will also display annotated games (though it usually won't display any introductory annotations before the first move).  There's also ChessX which looks relatively decent, but I'm not sure how much it will meet your needs.  They're both free, though, so worth a shot.  CheesX runs on Windows, OS X and Linux.  ScidvsPC includes a Mac version, but I can't remember if Linux support is native or needs Wine.

Both of those programs support exporting the PGN to HTML, which is good enough for web pages, but conversion to alternative mark up (or down) languages doesn't seem to have enough demand to have encouraged any development in that field yet.  You might need to code it yourself or conspire with one of the projects under active development to do so.