4: Support references 

Resolve references in FXML documents
4: Support references 

Renamed method and added unique test for IDs
4: Support references 

Added test for registry.
4: Support references 

Added test to check that IDs are unique
4: Support references 

Added check that method names are unique.
4: Support references 

Added test for link method. Needed to remove final from
ControllerAccessor for test purpose.
4: Support references 

Suppress warning