The encoding.html page was generated incorectly, revamp the input
xml.html and convert the full XSLT chain to use and serve it as
UTF-8
* doc/*: fix xml.html, update all stylesheets and regenerate
* Re-generated the documentation (API chunks 27-29 were missing)
(also causes changes to testapi.c, elfgcchack.h and
win32/libxml2.def.src)
svn path=/trunk/; revision=3574