Made d:ref/@href relative, added try/catch for px:info, modified tests

     - fileset-add-ref: d:ref/@href made relative to base-uri(parent::d:file)
     - fileset-copy: catching dynamic error thrown from px:info when
       directory doesn't exist
     - added test script for fileset-add-ref and updated tje test scripts
       so that they are easier to run. Run src/test/resources/test.xpl to
       run all the tests and generate a report in file:/tmp/report.html