- Finish tests
- Add error codes and better error reporting
- Compile a feature list of supported DTD commands
- Read <!DOCTYPE ..> and get the DTD in XML_Validator
- Create a real php script instead of "tests/test.php"
- More TODO's inside the comments of .php files
- Improve documentation
- Add setOptions() to DTD parser and XML parser

WISH:
- Build a DTD Validator
- Use directly sax instead of XML_Tree for partially
  validating instead of consuming a lot of memory
  creating the xml tree