first simply implementation of a sax interpreter
refactored the sax parser

* renamed the class from SAXParser to SAX
* added the Wasabi.sax method from specs to lib
* added the Wasabi.interpreter method from specs to lib
* reorganized spec support
implemented some more methods on the interpreter

* target_namespace
* element_form_default
* operations
refactored interpreter#operations
don't cache stuff just yet
basic support for multiple schemas and types