* Documentation updates.
* Documentation update for JavaFX DatePicker bug.
* NoteDialog: added new ViewModel class NoteModel.
* NoteDialog: use of JavaFX binding between UI controls and ViewModel.
* NoteDialog: use ControlsFX validation support for dialog validation.
* NoteDialog: use ControlsFX validation support for dialog validation.
* NoteDialog: removed unused custom validation.
* Added helper class ValidationUtils for common validation purposes.
* Added unit tests for ValidationUtils.
* Use of ValidationUtils in Note dialog.