* include/vaucanson/xml/xml_chooser.hh,
	* include/vaucanson/xml/node.hh,
	* include/vaucanson/xml/xml_converter.hh,
	* include/vaucanson/xml/tools.hh,
	* include/vaucanson/xml/xerces_parser.hh: Fix some include problems.
	
	* include/vaucanson/xml/XML.hh: Move macro definitions ...
	* include/vaucanson/tools/usual_macros.hh:... here.
	
	* include/vaucanson/xml/if_tag.hh,
	* include/vaucanson/xml/if_tag.hxx: Delete. These files are inaccurate
	at the moment. They will be fixed and re-added, if necessary.

	* include/vaucanson/xml/strings.hh: Remove a bad include.

	* doc/xml/vaucanson.xsd: Fix monoid and semiring order for 
	transducers. 
		
	* include/Makefile.am: Fix and update.