Moved out the NumberedJTextArea into its own class. It now manages the associated Undo and RedoButtons itself, so that the undo/redobutton code and their listeners are also moved out of FormatConversionDialog. Tested that it all still works, including bugfix to previous commit by overrding undo/redoLastAction() in NumberedJTextArea.java. 2. Also, cleaned up import statements, minor change to comments in the StreamGobbler classes, added the license text at the top of all these new classes.