Update: PCLVisualizerInteractorStyle inherit from vtkInteractorStyleRubberBandPick

Change base class of PCLVisualizerInteractorStyle to
vtkInteractorStyleRubberBandPick which will enable area selection.
Override vtkInteractorStyleRubberBandPick shortcuts so that they don't collide
with existing ones.
Update MouseEvent to handle the selection mode.
Setup callback and signal for the area picking event.