Changes since 28-May-01

General changes:
* replaced Sergey Melnik's rdf-api-2000-09-03 with 
  latest version rdf-api-2001-01-19
* optional drawing of literal-valued properties as node content
* optional drawing of non-literal-valued properties as node content
* added: selection of node background colour
* added: optional display of additional messages
* Modulename changed from RDFSchemaGrapher to RDFSViz

Servlet changes:
* added: link to the generated dot file in the result HTML page
* selection of the dot tool (version 1.7c or version 1.7.7)
* RDFSViz messages displayed in the restult HTML page
* Image type selectable

Application changes:
* added: xerces-1.4.0 for XML parsing
* verbose mode added
* added: application setup through a XML config file