XLink Schema Update

Hi

Thanks to Bob Schloss <rschloss@us.ibm.com> that pointed an error at 
my XGMML XML Schema. 
 
http://www.cs.rpi.edu/~puninj/XGMML/xgmml.xsd

Since I need to define some xlink attributes, I updated the XLink schema of
OPENGIS (http://www.opengis.net/namespaces/gml/core/xlinks.xsd)

You can find the new XLink Schema at:
http://www.cs.rpi.edu/~puninj/XGMML/xlinks-2001.xsd

Hope someone find it useful.

John Punin