temporary libxslt dependency

Right now the HEAD of the Silva CVS repository depends on the Python 
bindings for libxslt. This hard dependency will be removed again 
A.S.A.P. and at the very latest before the release of Silva 1.1 but 
right now Silva will not run without it. This is because of a new 
alternate rendering method that uses xslt-stylesheets instead of 
XMLWidgets. Anyone feeling brave enough is encouraged to check out the 
head and play with it/try to break it. Any feedback is very welcome. 
Right now there are only 2 renderers: the basic html renderer (this uses 
the old xmlwidgets system), and a renderer that tests the new system. It 
is called 'Images on the Right', and unsurprisingly, it renders a Silva 
Document in a table with two columns, with the right column containing 
all if any images in the document. Switching renderers is done from the 
metadata-tab. The code may not be 100% stable yet (but it will be soon), 
so developing against it is not recommended for now.

Eric "We apologize for the inconvenience." Casteleijn