[xml] xsltApplyStylesheet modifies doc

[François Delyon <f delyon satimage fr>]

It seems reasonable to expect that xsltApplyStylesheet should preserve  
the input document.
It is not the case since it calls xsltApplyStylesheetInternal which  
modifies the children of the
document in order to hide the doc->intSubset.
This modification is not reversible since, as fas as I unsterstand, it  
destroys the linkage even in doc->intSubset.

Nevertheless, I think that xsltApplyStylesheetInternal should be  
encapsulated in another function ensuring that the document
is preserved.
By the way, I don't figure out what is the status of doc->intSubset. I  
understand it is a shortcut to reach the dtd, but is it supposed to  
retain the linkage of the dtd children?

François.