implemented tree navigation class.
added some functionalities (i.e. check if a class has associations)
tree navigator initialization and attachment to the file manager
FileManager made dependent on TreeNavigator; started removing Node dependencies (Node.hasToggle() not used anymore)
removed TreeNavigator initialization from main class
(TMP) comment out .hasToggle() method
Virtually removed all dependncies on Node and ChildPartition
removed dependencies on Node and ChildPartition classes
refactoring: from Class to Classifier
REFACTORING: implemented tree navigation
removed dependencies on TreeProcessor, Node, ChildPartition
Physically removed unused files
removed dependency on Transformation, unused import statements, unused methods