Added the old_value parameter to text-changed handlers.
Implemented TextUndoGroup to be a specialization of UndoGroup. Added TextNodeUndo.
Text changes should trigger a redecoration.
Change to texts are now recorded using TextNodeUndo or DOMUndo (when whole nodes are removed or added).
Documented and reformatted.
Removed some code that turned out to be useless.
Added support for jsdoc parameters.
Added documentation.