Ontology editor: add basic window tool infrastructure
Ontology editor: add basic backend
Ontology editor: add basic ontology display
Ontology editor: allow adding of new relations and classes
Ontology editor: display available relations and classes
Add a synchronous ajax call helper method to tools
Ontology editor: add error output helper method
Ontology editor: add short type documentation
Ontology editor: add label to classifiation tree
Ontology editor: rename backend methods for class and relation retrieval
Ontology editor: add classification relations display
Ontology editor: add classification classes display
Ontology editor: add feature to remove relations
Ontology editor: add feature to remove classes
Ontology editor: be more verbose and utilize response handling function
Ontology editor: make relation removal more verbose
Ontology editor: treat the root node of the class-class links special
Ontology editor: add feature to remove class-class links
Ontology editor: exclude root classes from being shown and removed
Ontology editor: mark jsTree nodes as leafs if they have no children

Without doing this a jsTree node would show a small plus sign in front
of it whatsover. It vanishes if clicked on and there are no children.
Therefore it shouldn't be displayed in the first place.