This is to test XMLCatalog for external entity resolution from the
xslt task, both the simple case and using the document() function
to refer to a second file (which refers to the entity). This
buildfile is called by
org.apache.tools.ant.types.XMLCatalogBuildFileTest.java
Alternatively, you may try it out by hand by first removing the
comment symbols around the echo statements and then calling
ant -buildfile xmlcatalog.xml