Well, I have written a small extension that provides a simple API to store custom data in
the ParserOutput object and in the QuickTemplate object. In order to make use of it, I
would like to have a hook in SkinTemplate.php right before the QuickTemplate is executed.
Therefore, I had to patch SkinTemplate.php for getting the hook. See
http://wikivoyage.org/tech/CustomData-Extension for detailed explanation.
Hans